Well, it depends on what you consider to be a 'front'.

If it involved direct and active warfare, then North Africa would be your best bet. Casualties were relatively light and even at the end the Germans surrendered their African forces long before any major health-disaster. The Germans lost fewer than 20,000 men killed in the whole campaign, and at the end of the campaign the entire Axis forces of 400,000 men surrendered to the Allies. They surrendered without major loss of life due to weather, starvation, or brutality. Contrast this to the Eastern Front where a similar number of men surrendered at Stalingrad (not just Germans, but Romanians, Italians, Croatians, and so on) and most of them died, due to the cold weather, their malnutrition, and the brutality of the Soviets who were far more harsh captors than the Western Allies.

If you consider fighting the air/sea war or anti-partisan warfare as to be the front-lines, then Norway is your best bet. The Germans took Norway rather easily in 1940 with pretty light casualties. They then held Norway for the entire war with rather minimal losses due to resistance, Allied air/naval strikes, and general accidents and such. The Allies never launched a substantial invasion of Norway so the hundreds of thousands of German troops there managed to surrender without much issue when the war ended.

For most of the war a posting in Germany itself would be rather cushy, but at the end it was invaded from both west and east so you would be quite likely to see active combat or bombing raids. The best way to avoid dying is to avoid combat in the first place, so Norway would be your ideal posting if you wished to stay out of dangerous situations.