Poli-Seal is pretty much my go-to, it just works very well for me. I'm sure it's loaded with oils/fillers, but the customers paying for one steps are never really concerned about swirls and marring. I usually just top it with Optimum Car Wax
I will also occasionally use ZAIO on cars in better shape and when I will be topping with a sealant. I used ZAIO on my gold Lincoln the other day and it seemed to do a great job cleaning up the paint and removing some light marring. Put Z2PRO on top and it looks awesome.
Klasse AIO is a nice product, but I was never too fond of it as an AIO. I used it with great success on rubber trim, wheels, etc.