I've got a few places I'd like to live and all of them involve what would be my dream job in PokéWorld haha. I'd like to run a ferry service! I love boats and I may as well make money off that. :D So, the best places for me to live would be Olivine, Slateport, or Lilycove. I like a bigger city, so not gonna go to Petalburg. And there's probably going to be more people coming and going by a mainland port than an island port, so not Cianwood, Dewford, or Mossdeep.
If I were living in Olivine, I'd probably get higher traffic once the Safari Zone opened, and maybe have people from Cianwood heading across to hit up the Frontier. Mossdeep's Space Center is probably a decent tourist attraction fro those stopping in Lilycove's hotel, while Lilycove's Art Gallery, Department Store, and Contests would bring some islanders over a fair amount. Slateport would probably pretty busy what with the shipyard and the marketplace; Dewford people probably come over all the time.
I honestly think I would choose a Hoenn city because I love Hoenn a lot. And Olivine looks windy as heck I bet it gets pretty cold. :( Slateport seems busier than Lilycove, but it's more industrial imo. So Lilycove would have more for me to do in my free time. And Mossdeep would be more fun to go to all the time.
tl;dr: Lilycove yo.