FO1? I would have to say Boneyard. Why? Lots of space for development and expansion. The way I see it, Boneyard is set up to be a major boomtown. No building places to live out of corrugated cardboard and rusting hot dog carts, just fix up some old buildings.
FO2? Have to be New Reno. Know the right people, do the right things, you are SET.
FO1: I hated the BoS. Why? Because they think they're the biggest thing, yet they don't have the balls to try and take what they can. Besides, Rhombus is a dick.
FO2: I hated Arroyo. I don't give a fuck about them, if I had a choice I'd just abandon them. Why go back to a fucking tent when you've got a car, a party, and some major hardware? I mean, after about level 10-12, you can rule just about anywhere in the wastelands.