Hmm... realistically, living at the base of Mount Targon is the overall safest as long as you don't do anything that causes you to be accused of heresy. Especially because not even Noxus seems to care about conquering it.
However, that's no fun. Bilgewater is a bit too cutthroat for my tastes. Piltover would be nice, but only if I'm upper class and well-defended if when Noxus arrives.
Freljord and Shurima are too low-tech for my tastes, honestly.
Ionia would be nice as long as I don't get killed by some magical creature/magic user I inevitably piss off. I also have to worry about Noxus coming in and ruining everything.
Demacia's too insular, I think. And there's also Noxus that's going to be coming at them some time or another.
Y'know, now that I think about it, Noxus seems to be a pretty decent place as long as I can pull my own weight. I think I'd be a pretty good warmason; I'm good at fast-talking.