Tetley original is my number one all time favourite drink, but I tried Twinnings strawberry and raspberry tea a few weeks ago and it's climbing the ranks pretty fast.
Aside from water? Probably Buffalo Rock Ginger Ale. That stuff is STRONG. The first sip is always careful, but every sip after that opens my nostrils and invigorates my body. I love it.
I really like to drink Diet Sunkist. I also regularly drink water and Lipton diet white raspberry tea. Oh and recently, I've taken a liking to Diet Mountain Dew. Plus there's also blue Powerade. ^_^