Every site has it merits.
I went through Riverside. Maybe not the nicest city to hang out in, but the flying was probably the best experience you can get for the money. Airspace, TER's, towering mountains, coastal fog, winds, occasional rain. 95% of the days are flyable.
I decided on Riverside, CA because I wanted to learn how to fly in all kinds of airspace. There are things you can do in Riverside that you can't do in too many other places. Example: Departed KRAL, T.E.R. to KCNO, made a slight turn to the I-CNO localizer got the straight-in clearance, and landed KCNO. My total "wheels-up" time was 0.1 on the hobbs! Beat that!
Decide what's important to you. (beach, near family, airspace, away from distraction, IMC, VMC, warm, cool, ... whatever...). You'll probably find it at one of the ATP locations.