Anything with caffeine, lovely, wonderful, insomnia-giving caffeine (who needs sleep, plenty of time for that later...)
As a cold drink- Coke, Dr. Pepper, and root beer are all good (IBC, S&W, Mug, Barq's... and no, can't evver have REAL beer, seizure meds for life, so yeah, for me, root beer has to count for the best cold rink...)
A hot drink- TEA!
Screw coffee, it's tea all the way, and so many great blends, black or green, English, Irish (VERY good and can give you a bit of a kick) Earl Grey, Chai... and then Oolong and Genmaicha and Jung Ching Dragonwell and a good deal more...