I can't stand Guinness but I like Harp.
I like Molson but Labatts always gives me a headache.
Beck's is a good buzz without much of a hangover.
Foster's is pretty good and also the only Australian beer I've ever seen around here.
The very best I've ever tasted is Great Lakes Christmas Ale. This is a Cleveland micro-brewery and not the cheap stuff from the 50's that someone mentioned earlier. The Christmas Ale comes out around the beginning of December and has flown off the shelves before the Holiday arrives.