With well over 200 countries to choose from it's hardly a balanced poll. I live in London and there are lots of nice girls here but they're not all English and certainly not all the same colour.
I like Swedes, Moroccans, and black African girls.
Man, these threads get so re-hashed some times. From that list, I would say German. I personally Irish are some of the best - Irish American girls that I run into quite a bit. :2 cents: Norwegian girls are killer too...