I'll drink basically anything that's not a drought (ie, guiness). But beers are situational for me.
*With food: Sleeman's Honey Brown (it's sweet and doesn't conflict with the flavour of your food)
*Outdoor pub: Stela Artois (it has that little bit of skunkiness while still being light and refreshing)
*Indoor pub: Boddington's (all the body of a guiness in a much lighter and less strongly flavoured beer)
*Just getting hammered with friends: Moosehead (the flavour is worth the extra $5 per 24 over the usual canadian beers {ie, Blue, Canadian})