I have; I think I've tried everything. I've tried instant coffee black, I've tried it with creamer, with sugar, with artificial sweetener. I've tried it at chain restaurants like McDonalds, I've tried yuppier places like Starbucks and a bunch of their concoctions, I've tried hipster independent places and different blends from them.
I've tried cold brew, coffee slushies, different quantities of frapp'd up milk, different coarseness of the grind, different types of beans, different roast levels, etc. and the only time it's tolerable is when there's so much milk and sugar in there that it's debatable to even call it "coffee" anymore. I can't even stand coffee ice cream.
I think it's just not for me.