i find Guinness Draught (fresh from the tap) wonderful..
freshest so far is from Muddy Murphy's
also from Guinness brewery, Kilkenny Lager.. also on tap...
the other stuff, Heineken... few come close to how refreshing this
stuff is...
our much maligned Tiger is pretty good too...
then the other stuff, like San Miguel, Stella Artois, Grolsch (i
forgot how to spell) and a few others i've can't think of now, is
also really refreshing 
also well liked is the stuff from the microbreweries like Paulaner
Brauhaus and Brewerkz (Pilsner) 