The minor Axis allies are the first obvious choice.

• Hungary. It was given southern Slovakia, Ruthenia, Transylvania, and border regions of Yugoslavia. After WWI the Allies cut Hungary down to a minimal territory. Any area of mixed ethnicity was given to anyone but the Hungarians. Hitler largely reversed this and anything that could vaguely be considered Hungarian was given back. They even got some areas that really couldn't be considered Hungarian.

• Finnland. They had a lot of potential areas they might get in Karelia, and of course they regained the territories taken in the Winter War. In a successful war, Finnland might have grown to twice its size.

• Bulgaria. They were given Eastern Thrace and Yugoslav Macedonia. That met most of Bulgarian irredentist desires.

• Croatia. When Yugoslavia was conquered and partitioned the Serbs were on the outs, and the Croats were the favored ethnicity. Post war the Croats were set to receive most of modern Croatia, Bosnia, and parts of Serbia.

Not all the European Axis were so fortunate. Romania lost territory to Hungary. They got a nice slice of the USSR in exchange, but that was mostly a wash.

Outside of them, it gets more speculative. Hitler was showing his hand during the war and we can see adjustments he made in Europe. What may have happened elsewhere is less predictable.

Part I

For Germany, "happy" is probably the wrong word to use in this case. Even before the war broke out, it was clear in Czechoslovakia that German occupation entailed a loss of national sovereignty, the imposition of German racialist policies, and incorporation into a German economic sphere that clearly prioritized the Reich. For the fascist and fascist-like political parties of Europe, all of these corollaries of German occupation or alliance were bitter pills to swallow. Even where there was some ideological overlap with National Socialism such as antisemitism, cooperation with Germany proved somewhat difficult. In Hungary, the partisans of the Arrow Cross in the early 1930s framed their antisemitism as a defense of "Christian Hungary" and only later 1930s did biological-based antisemitism gain fitful traction. German occupation and alliance meant having to adjust to German definitions of politics and surrendering authority over an increasing part of the domestic sphere to German representatives. So instead of being "happy" with German victories, a better word would be "accommodation". For the minor European powers and ethnic groups, German power was a reality that they had to adjust to, not something they actively worked to achieve. This adjustment process worked on several different push-pull axes that underscored the highly asymmetrical nature of German dominance on the continent.

One axis that pulled a umber of ethnic groups and states towards collusion with the Germans is the tantalizing prospect of score-settling and other forms of recrimination against other groups. The racial policies of the German state as well as its deliberately draconian military occupation policies accentuated and sharpened existing social fractures in areas the Germans occupied. This was readily apparent in the waves of popular violence in the Baltics and Western Ukraine in the wake of Barbarossa. These areas had only been recently incorporated into the USSR after the Molotov-Ribbentrop Pact and NKVD pacification and policing of these areas frequently involved violence and terror. When Germans occupied these regions, there were instances of spontaneous mob-violence such as the storming of jails or targeting Soviet collaborators. For their part, the German occupation authorities fanned the flames of these hatreds by actively publicizing the discovery of Soviet atrocities like Katyn and channeling hatred towards racial enemies. Preexisting antisemitism thus became "weaponized" to an extent as Goebbels's propaganda machine built on preexisting associations of Jews with the NKVD and Bolshevism in a way that made the situation more conducive to popular pogroms and local collaboration with the Einsatzgruppen in rounding up the Jewish population. This was, of course, one dimension of the score-settling the Germans enabled. Antirepublican political opportunists in Vichy used the ignominy of defeat to purge out various political enemies they had made in the interwar period and try to restore France to national glory. One of the most prominent of these advocates was Edmond Vivier de Streel, an industrialist and former cabinet chief of the Colonial Ministry. Vivier de Streel envisioned France as the colonial power within a German-dominated Europe; it would be the standard-bearer of European civilization and act as a source for colonial products for German-dominated metropole. But unlike the Western regions of the USSR, there was little room for cooperation with their Western European allies, and thus political purges never really resulted in a new order taking shape under the Third Reich. Industrialists in the Low Countries who might have welcomed the anticommunism and anti-labor stances of an NSDAP-like movement, but instead found that German occupation made far bigger inroads into their concerns than either organized labor or the Communists had ever achieved in the interwar period.

Score-settling could also take place on a national scale and Germany's unprecedented and swift occupation of the continent seemed to offer the chance at territorial revision that would undo the Versailles border system. Some of the minor European powers did see potential benefits with aligning themselves with Germany. But territorial revision soon proved to be a poisoned chalice at best, and it was soon apparent to many Europeans that the only real consistency Germany had was territorial revision had to serve German interests. Both de Streel and Paul Baudouin, the Vichy foreign minister, were apoplectic about the Japanese takeover of Indochina in 1941 and Berlin's indifference over their complaints. Other European leaders sought to gain German approval and support for redrawing their national borders and expand their territories. Finland arguably played this game the best of the Axis satellite states by using its relative geographic distance from direct German power to wring promises of territorial concessions in Karelia and military aid. But Mannerheim and the rest of the Finnish leadership tended to be more realistic about German's chances than the other Axis powers, and Finland never really overplayed its co-belligerent status and still had diplomatic channels open to the West, and by extension, the USSR. Thus Finnish negotiators could leverage German military aid consisting of modern equipment in 1943, which in turn allowed the Finns to conduct a fighting retreat from Karelia and open up negotiations with the Soviets for an end to hostilities. But the Finns were atypical for the Axis satellite powers. Territorial revision could either come at the expense of the USSR or among the other Eastern European states. Neither prospect was productive for a German-run new order which saw the East as Germandom's own territory, and reserved the plum areas for Germany, and inter-Axis revisions heightened tensions within the alliance.

The failure of Barbarossa counter-intuitively gave the satellite Axis states some leeway with their German allies to gain access to modern military equipment and other concessions. The Slovak government in 1942 requested that its two divisions be removed from the Eastern front unless Hitler made good his promises to reequip these formations. The Slovak Premier Tuka also wrestled out guarantees of postwar arms supplies, asserting that the while the Slovak state "valued the protection promised by Germany, but the protection [should] not be that of the sheepdog for a flock of sheep." However, pressing the Germans too hard for concessions was a dangerous game since it invited Germany to cut the Gordian knot and occupy the country. One of the important stratagems for the Eastern European satellite rulers was that the German alliance bought them support against their own radical right-wing elements in their own domestic spheres. In Hungary, Admiral Horthy was able to use German support to muzzle the Arrow Cross in the early portion of the war and likewise use German dependence upon Hungarian resources to fend off German encroachment on Hungarian sovereignty. But this tactic was always a double-edged sword as it only emboldened these political elements and provided the Germans a willing cadre of collaborators should they decide to occupy the country, as happened in Hungary in 1944.

The polycratic nature of the Third Reich also made it easier for these allies to cut side-deals with various German power blocs to retain independence. Industrialists in France and the Low Countries tried to cozy up both with the Ministry of Economics, which was under Göring's purview, and the German military to stave off German business takeovers of their firms. In Eastern Europe, the SS became one of the favored power blocs to make alliance with, as the SS was forbidden by agreements with the Heer to avoid direct recruitment within the Reich itself. But accommodations with Himmler often entailed giving into demands for congruence with German racial policies and active participation in genocide. Likewise, Western European industrialists often to meet Germany's ever-expansive production quotas and contend with a workforce that had its rations cut because of German food requisitions and whose domestic economy cratered because of German occupation policy, which verged on systematic plunder. While the the existing antisemitism within Europe ensured that ethnic cleansing and genocide was less of a moral issue for some, collusion with the worst excesses of German occupation made collaborators hostage to German military fortunes. Germany's losing the war could mean a firing squad and other forms of recrimination for the people closely associated with the German occupation.

What this all meant was that whatever alliances Germany managed to form with states or various ethnic groups was quite shallow and highly contingent on circumstances. The reorientation of some of the "Little Entente" to Germany in the late 1930s was not so much a reflection of ideological affinities with the Third Reich as a calculation that the post-Versailles collective security arrangements had failed after the Munich agreement and the situation presented an unappetizing choice between a Soviet or German alliance. Going it alone was dangerous and invited dissolution, as the fates of both Yugoslavia and Poland showed. Werner Best, one of the architects of the SS's RSHA, arguably had one of the more coherent plans for German occupation of the continent in which collaborators in racially-sound countries like France, Scandinavia, the Low Countries would operate under German "supervisory administration" as they adjusted to the new order the SS remade in the East. But Best's vision was undercut at multiple areas by both the shifting power blocs within the SS as well as the needs of the German occupation policy that favored expedient solutions to organizational problems instead of engaging in constructive solutions with non-German fellow travelers.

Romania would have been an interesting case. It lost a large part of Transylvania (to Hungary), and Southern Dobruja (to Bulgaria) but regained eastern territories formerly lost to the USSR due to the Molotov-Ribbentrop Pact.

Losing northern Transylvania permanently certainly would have been a moral and economic blow. The country gained the territory of Southern Dobruja from Bulgaria, after WW1. However in contrast to Transylvania, there were basically no historical claims to this region, and its loss after Molotov-Ribbentrop was much less important.

The northern and eastern regions of Bukovina and Besarabia were ceded to the USSR but regained later during the war on the eastern front. These territories, as part of the Moldovan region of Romania, were also perceived as important to national unity and historical claims. So, bittersweet for Romania overall, losing parts of Transylvania but regaining parts of Moldova.

To theorize, had Germany not been defeated in the east, it is possible Romania would have been granted parts of Ukraine bordering Moldova (including important cities such as Odessa).

I am surprised nobody mentioned Spain that came out of a Civil War backed by Germany and Italy and would have probably be allowed to expand its influence in North Africa at the expense of France and recover back places like Gibraltar from British hands.