I'll bite. I'm still new to drinking/brewing craft beer, and I'm a young'n so my memory is relatively intact.
As for the best beer I have drunk, I must choose the bottle of Bavarian lager that my friend brought back for me at Castle Neuschwanstein. I've drunk lagers before, but I typically go for ales. Well, I guess as it is written in some holy text or another, "and the scales fell from my eyes..." It was like drinking spun gold mixed with cloudstuff.
I'm still very pleased with the oatmeal porter I made last year. But I expect many of the beers I make in future will be "bests" until I get a better handle on water chemistry!