I like American girls. Not the high-pitched annoyingly whiny ones, but the more well-spoken ones.
I'm also a fan of Welsh Valley accents on girls, if only because they sound so utterly filthy that its very easy for sex with them to become almost porn-like in it's execution.
I despise the Yorkshire accent on women. Hard countries breed hard women, with hard accents... On the subject of Yorkshire accents, I've found in my travels that Americans struggle to differentiate between my Yorkshire accent and what they perceive a Scottish accent to be. Not a whole lot to take from that, but I found it quite interesting.
Oh, and on the subject of Irish accents - The soft southern ones are okay I guess, but the Northern Irish accent is just horrible.
Overall. I'd say a difficult subject - it's easy to say you like accents from X country, but then, countries tend to have a lot of different regional accents. Britain is a great example, you get people from Belfast, Glasgow, Edinburgh, Newcastle, Leeds, Manchester, Liverpool, Birmingham, Bedford, London, Exeter, Bristol and Canterbury in a room together, there's going to be a lot of sentences being followed up with blank looks of confusion.