Cans if I have to buy for takeaway. Bottled "beer" (or lager to everyone outside the US) is scandalously over priced in bottles, and an utter waste of money for tasteless rubbish.
I'm a beer drinker by preference - and I mean real beer, not the gassy pish that people insist on calling beer, but I always find that bottled ales never quite taste the same as they do out of a barrel, and for some strange reason always seem (to me at least) to have a slight fizz to them.
Bitters and heavies from a can seem to suffer the least in comparison to a proper pint in a proper pub so that's what I'll buy. I do most of my boozing down the pub though. If I'm drinking in the house, which isn't that often, I actually prefer a bottle of red wine though.