If i'm in a proper pub i'll always have a cask over keg. However, lots of places don't do cask, or will just do a token 1 or 2 ales, which aren't kept well.
For home-buying, i prefer the smaller cans over glass bottles. Just purely over aesthetics. Taste wise, can't really tell.
Different with soft drinks though - will generally avoid plastic bottles, as it seems a lot worse. Cans in the main as you can't really get glass bottles now (apart from Coke)