There's absolutely no substitute for choice, in any respect.
I settled in London England for the last 15 years; arguably the capital city of the industrialised world, with some 8-9 million people. I always remember coming back from having visited my provincial home town that has a population of approx 250K. There are always more hot women in London; as soon as you arrive back and get off the train, you notice it. It's pure numbers is all.
It is worth thinking about population/ethnic demographics though. Think about what, if any ethnicity attracts you. For example, I plan to live in Manchester at some point, because I like the city (smaller, but similar vibe to London) and there are 2-3 generations of Spanish-Italians there. Some of the Anglo-Latin mixed girls are among the most beautiful you'll ever see, plus they have the more traditional, laid back Northern temperament; the perfect combination