I also haven't been to enough cities, but out of the ones I've experienced thus far, it'd have to be the one I'll be living in here in about a month and a half and that'd be Seattle, Washington
I've been to dallas, houston, ft. worth, austin, san antonia, los angeles, san diego, oklahoma city, albequerque, etc..etc.. basically most of the major cities from texas and west onto california. By far I've absolutely loved Seattle the best. Some of the other big cities were nice to visit but I never had the feeling I wanted to live there but seattle was different.
One day I hope to travel to Japan as well as Ireland though. Perhaps australia too assuming I can get the others conquered first