For me it has to be 100% black, invariably.
I like my coffee unflavored,* black, strong, organic, fair trade. Espresso is my favorite.
*I dislike the commercially-added flavorings. But once in a while I might add certain spices while brewing it-- cardamom (Indian and Arab custom), cinnamon (Mexican), or even ginger (Yemeni). Indians sometimes spice their tea with chai masala and apply similar spices to coffee too: a blend of cardamom, cloves, cinnamon, black pepper, and ginger. If you make filtered drip coffee, do not add powdered cinnamon to it, because in hot water it turns into a thick colloidal goo that won't let the water go through the filter. Use a broken-up cinnamon stick. I once had Arab coffee with mint leaves added, which was surprisingly good.