Oslo and Stockholm cannot be beaten. The girls are really really friendly and love getting a chance to show off their English.
As for which I prefer, well there are less people in Oslo but almost ALL of the girls are super hot. In a weekend there I saw one fat woman, and she was a tourist. In Stockholm you do see super hot girls but you also see some fat/ugs.
If you took 100 women at random from Oslos main street (karl johans gate), 85-90 would be really hot. If you took 100 at random on Stockholms main street (drottninggatan) about 60-70 would be super hot. If you took 100 at random from Dublins main street, you would be lucky to get 20-30 hot girls.