AIO/UPP
I'm just an amateur, but, from my experience, Jngrbrdman is right on. We have two daily drivers, so, I use AIOx2, SGx2 on my wife's car (parked outside) and AIO, SGx3,UPPx3 on the other car parked inside most of the time. I get about 6 months on my wife's car and close to 10 or 11 months on the other car. Basically, it seems to me that the UPP is gone long before the SG on the inside car.
However, thanks to Jngrbrdman (see his great detailing thread) and others on this site, when it comes time to do the cars again, it is much easier than the first time I did them. It's all in the preparation. Not only do the car look great in the beginning but they really look good when it's time to go over them again.
We just took my wife's car to the insurance office to show them the mileage. It's been parked outside in the central valley for 1 year. The AIO/SG is now gone. (I'll be going the car next week.) But when the insurance representative saw the car, she said, "That car can't have 130,00 on it. Did you repaint it?"
So, for durability, go with AIO + SG. But UPP looks really good over the SG!
