Hoping not to commit one of those hideously blatant mistakes, which in this case would be not reading five pages of people posting their favourite drinks and while answering to just that question missing out of the recently formed discussion about world economics, I'd like to add my own imput.
I think, and the inherent problem with this (not thinking, jeez, I mean what I am about to tell you) is that my tastes do tend to change with the cruise speed of a flying jet, that right now my two favourite drinks ... ok, three favourite drinks are: tea, coffee, and flavoured mineral water.
In the first department (yeah, I mean the tea) I'm quite fond of making mine half and half, half water and half milk. I don't use sugar, but some diet products which in my egocentric opinion, just taste better. As for coffee, it's more of a tricky business. Let's take instant coffee for now. One and a half spoons of instant coffee, half a spoon of sugar and one of those little envelopes containing that diet sweeter (or whatever you English natives would call those kind of things), topping it off with a spoonful of grated chocolate; mix with five or six drops of water (and I mean it, quantity is very important, you may add a few more drops at your own risk) and finish it with 4/5 of hot water (not boiling) and 1/5 of milk.
Well, now that I've said all that about coffee, I just feel kind of silly just saying apple flavoured mineral water.
But you should see how tasty it is