Tea (HOT!) is my personal favourite, but that's what I grew up on. Barry's Red or Green label. (Irish tea, best in the world!)
Coffee, have to say - a close second to my tea. Ranger coffee is an excellent pick-me-up in the field.
Cold sweet tea - this is a gift from the God's in the south, and actually pretty good on a hot muggy day.
Cold coffee - horrible, terrible - and I question the validity of someone's mental state (or maybe just their taste buds) when they intentionally take measures to make it cold.