Really depends on mood/occasion/hormone levels/thirst/type of food/outdoor temps... etc... etc... etc...
Currently, with late summer messing with my intention to get used to the cold nights by bombarding me with sunlight, I still generally prefer a cold one, but today's favourite would be pretty much any Trappist beer, with me being partial (for no proper reason) to Orval or Chimay.
Come on, highest-quality, delicious, thick-foamed beer that's brewed by monks in a monastery, sold in a decidedly non-profit fashion, with excess money going to charities - what's not to love about that?
Also, wrap your head around the idea of beer that gets better as it sits in the bottle, merrily awaiting your craving as you pull it from the cave?
Another favourite of mine would be Lambic.
Brew your beer, leave it exposed to the open air and invite friendly yeast and jolly bacteria to plunge in and do their thing.
http://www.jamesclay.co.uk/beer-suppliers/images/stories/product_pics/orval.jpg