I'm trying to replicate the spice mix used for Döner Kebab. I am interested in spice combinations from any area. However, I am most interested in which spices are used to prepare it around western Germany or more specifically near Ruhr University.    I've looked far and wide and tested many concoctions of herbs, spices and ingredients.  I've pinned down a few spices that to me makes very tasty, nearly authentic Döner Kebab at home: onion, rosemary, and marjoram (or oregano as a possible substitute, but preferably not). Possibly a bit of cumin but not a lot.  I'm already familiar with the meats and process used; I'm particularly interested in just the primary flavoring ingredients, so that I can finally pin down the most authentic flavor possible. 
From what I can find from various sources in German, a typical "Döner spice blend" includes a lot of black pepper and salt, followed by oregano or marjoram, garlic powder, onion powder, cumin, and cinnamon. Additionally, most retail products include an instant broth powder, and a fair dose of MSG or related "flavor enhancers".  Most products will have some additives to help keep the ingredients free flowing (dextrose or similar), but you won't need that to replicate the dish.  Additionally, I'd expect to see some sweet or piquant Hungarian paprika in most recipes, though in the German sources I spotted, it wasn't always in the off-the-shelf blend itself; I imagine people like to feel like they are "customizing" the seasoning by adding their own preferred levels of some ingredients.  This is pretty consistent with my memory of experiences eating Döner in Hessen, though the last time I had Döner Kebab was circa 1992 and I haven't eaten meat for a very long time. I am fairly certain that a substantial quantity of MSG is used at most German Turkish shops.  If you want to get a close approximation of the dish, consider searching for recipes for Iskender kebap. I'm not 100% sure that yogurt is part of the marinade for Döner, but it's a closely related dish and the seasoning appears similar. 