It depends on a few things: weather, mood, location, what's on tap? At home, bottles of Anchor Steam (nice to know what the Maytag family did with their money) or Sierra Nevada. At my local bar, they have Ommegang Ale (either Rare Vos or Hennepin) from upstate New York on tap, along with Chimay wheat for hot days. If I'm in the UK, an ESB on tap works, in Germany a Kolsch or something else local (Riegeler is my overall favorite, but not exactly easy to find outside Freiburg), etc.

So it all depends. There is no one best beer, except for the one you're drinking at the moment :-)

Bob