Ah… well, this is sort of the historiographical debate regarding WW1, and there are several sides to the issue. If you want an extremely short version, people have written books blaming every single belligerent power (often titled some variation of “_____ and the Origins of the First World War”), but the most popular theory at the moment is that Germany bears more (but not all) the blame for the war. However, there are credible historians advocating other views, so it isn’t anywhere near as black and white as historiography on WW2.

The “blame” for World War 1 was extremely controversial from basically the day the war ended, with the inclusion of a “war guilt” clause in the Treaty of Versailles. Although the intent of including it was more for legal reasons than anything else, it caused a huge storm of controversy. Germany had agreed to an armistice based on Wilson’s 14 Points and a “Peace Without Victors”, which swore off monetary reparations that didn’t correspond to war damages. Traditional diplomacy had monetary compensation as a common element of peace treaties (see the treaty that ended the Franco-Prussian War), but that technically wasn’t an option in this war. Technically, the Entente could only demand reparations for the rebuilding of Belgium and Northern France, which was at odds with the promises Entente leaders (particularly the UK) had made to their populations during the war. The war guilt clause was basically there to say “Since this is all technically Germany’s fault, we can demand money for the damages suffered by our population and economy”. A point to note is that a similar clause was included in treaties with Austria and Bulgaria, which was not contested by those nations. However, the Germans did not react well to the war guilt clause, and it became a major point of contention. Writings in the interwar period show a clear divide between Entente writers (naturally supporting Germany’s guilt) and German writers opposing it. This remained an issue because the political struggle over reparations continued throughout the 20s, so proving one side or the other could translate into real money. As an example, when the Weimar Republic released their documents about prewar diplomacy, the collection was heavily edited to paint Germany in the most positive light. Of course, the black and white nature of war guilt in World War 2 changed things. Currently the most influential point of view is a variant of the “Fischer Thesis”. Fritz Fischer was a German historian who, in 1961, published “Griff nach der Weltmacht” (Germany’s Aims in the First World War), which postulated that Germany had an expansionistic and aggressive foreign policy, and bears primary responsibility for the war. Furthermore, he argued that their war aims had remarkable continuity with Nazi war aims. As you can imagine, this caused a storm of controversy in post-ww2 Germany. He was one of the first historians to have full access to unedited German archives, so his views were taken very seriously and became the dominant viewpoint. However, over time, the dominant view has shifted somewhat, becoming more mollified and, while still blaming Germany, putting more blame on other powers and on systemic factors (alliances, imperialism, nationalism, militarization).

As for other viewpoints, like I said earlier, there are historians blaming nearly every power for the war. The most prominent other targets are the UK, Austria-Hungary, Serbia, and Russia (France and the Ottomans don’t really get blamed). The viewpoint placing the blame of the war on the UK has been thoroughly discredited, but the anti-Russian theory received a boost due to better access to Soviet archives after the end of the Cold War. Ultimately, however, these theories are in the distinct minority. The final viewpoint, which I personally subscribe to, is that no power deserves an inordinate amount of blame, and that the war was a product of rational actions undertaken by all parties to protect what they thought was their national self-interest, which often conflicted. This view is, in my opinion, growing as the distance from World War 2 grows, but it is still in the minority. A recent book that advocates this position is The Sleepwalkers by Christopher Clark, which I would highly recommend.

Ah, well, I just realized that all that wasn’t exactly what your post was asking. But I already wrote it so I’m gonna keep it in.

The question of “Evil” in the war is also really difficult, in large part because of the inevitable comparisons with World War Two. Germans were undoubtedly evil aggressors in the Second World War, and are popularly perceived as aggressors in the First, so shouldn’t they have been evil in World War 1 as well? There’s also a wealth of American, British and French wartime propaganda that is fairly commonly seen or referenced: the famous references to the Germans bayoneting Belgian babies, referring to the Germans as the “Huns”, etc. There’s also the fact that the Entente was mostly made up of democracies (with the very notable exceptions of Russia and Serbia), while in the Central Powers, autocrats retained significant power. This image of democracy vs autocracy was intentionally cultivated, especially after the 1917 Russian Revolution and the entry of the US into the war, and the advent of Wilson’s 14 Points. As /u/elos_ rightly pointed out, the Rape of Belgium happened, and the occupation of Belgium and northern France was not pleasant in the slightest. However, despite all of that, the moniker “evil”, especially when compared to the Second World War, can’t be attributed to any side in the First World War. Although the Germans did not treat Belgium and France well by means, the atrocities can’t be attributed to a systemic policy by Germany, and, as overblown as the fear was, can be attributed as a reaction to fears of guerilla warfare. Similar incidents didn’t happen to nearly the same extent on the Eastern Front of World War 1, despite a larger population under occupation. For both sides the war in Africa was exceptionally brutal for the local population, and thousands of Africans were pressed into service, used as forced labor, or starved to death due to fighting. The large populations in British and French (and Ottoman and German) colonies were subjected to the draft against their will. For every one of Germany’s nakedly imperialistic and territorial desires, similar desires can be attributed to France, Britain, Russia, Austria-Hungary, Bulgaria, Serbia, Greece, Italy, Japan, and the Ottoman Empire. The Entente proclamation of “National Self Determination” was necessarily hypocritical: why did the French in Alsace-Lorraine deserve self-determination, whereas the Germans in the same area (and in Austria, the Saarland, and possibly the Rhineland) not? Why did the Arabs deserve independence from the Ottoman Empire, but not from the Anglo-French empires? Why did the Romanians in Transylvania deserve it, while the area’s German and Hungarian population not? Why should Cameroon be an international mandate, while Nigeria shouldn’t? And so on and so forth.

My point is, no side or state can be perceived as moral in World War 1, and no state was more “evil” than another. Venturing into hypotheticals, it must be noted that the majority of the war occurred in Entente territory, and it is possible that an Entente occupation of Central Powers’ territory might have been just as bad. For example, the Russian occupation of Austro-Hungarian Galicia during the first year of the war was not kind: Jews, religious minorities, local nationalists, other nationalities, basically everybody anti-russian, were oppressed, arrested, exiled, and/or deported. The occupation was so bad that a member of the Russian Duma called it a national scandal. Many in Germany called the continuation of the British blockade (leading to partial starvation) after the armistice was signed, a war crime.

Edit: Regarding the "nobody was more or less to blame for the war" theory, the best way I have heard it explained (by a professor) is this:

To assign blame to one power (or one side), you basically need to decide that that side's national self interest was not valid.

Austria's desire for influence in the Balkans' was less valid than Russia's desire for influence and pan-slavism, or Serbia's irredentist desire for a unified South-Slav state. Germany's imperialist desires were less valid than Russia's, France's, and Britain's. The Ottoman Empire's control over their Arab subjects was less valid than the British and French control over their Arab subjects.

That's the reason why I subscribe to the "nobody is to blame" theory: I don't think that anybody can objectively say that one state's national self interest is better or worse than another state's (in a pre-20th century ideology and human rights era). World War One is one of, if not the, first conflict that has moral standards applied to each side's war-goals. In the 19th century, you don't really see moral standards applied to imperial rivalries: nobody really argues whether the Russian Empire was right in desiring the Straits of Constantinople or if Britain was right in its desire to protect India and the Suez Canal: the desires of states are simply accepted as fact. However, this is not the case in World War 1.

In regards to the who was seen as the bad guy narrative and who was more expansionist/aggressive, I'd suggest this in depth post I made a few weeks ago on a very similar topic. Especially at /u/estherke's analysis below mine with regards to German atrocities in Belgium. Hopefully that answers your question.