The weather will be nicer in AZ but Texas will be cheaper. Any where from Phoenix south and west will be nice. South east from Tucson is higher in elevation and will be cooler. Casa Grande south of Phoenix is a popular area.
I have had both and liked the installed best. If you plan on spending most of your time in RV Parks I would not even get a generator. The on board generator is nice when traveling and stop for lunch. If you are parking on public land and boondocking a portable is nice because they are not as loud in the trailer.
You must unhook and move the truck away before doing the auto leveling. The trailer drops the front end first to assure you have unhooked. You can manually level without unhooking if the site is level.