Lets see....
When out in a pub here in Dublin, usually Guinness. Outside of Ireland, however, it's normally shite. In England, it's alright. The effluent sold as "Guinness" in the USA is a fucking travesty that should never have been created. It's not even vaguely the same drink. When in the USA, I tend to drink Sam Adams, as about the only drinkable beer America has ever produced. You guys are good at some things, beer is not one of them.
I spent a year in Belgium, where there are many, many good beers. I learned to love Kwak, Chimay Bleu and the ludicrously powerful Delirium Tremens (which even has a pink elephant on the label...), among others.
My current favourite bottled beer is a very flavourful and refreshing German number by the name of Edelstoff. If you get a chance, give it a go.
Other beers I'll happily order at a bar include Grolsch and Stella Artois, and if the weather is right and there's a football match to watch, I'll sometimes feel the desire for a pint of cider, Bulmers (sold as Magners outside of Ireland) by default, but Koppaberg is a preferred alternative.
I also have a fondness for certain local brews. Anyone familiar with, or intending to visit, Dublin, should take a trip to the Porterhouse, and have a few pints of Plain, Oyster and Wrasslers. And then see if they've got any of their "Hemp Beer" in stock. Holy shit, but does that stuff do odd things to a man. A night of Hemp Beer leads to tales that pass into legend!
Dammit, now I want (another) beer.