Ask ten people and get ten different answers!
I used the NuFinish for years on all my vehicles and tt's. It's not a wax, but rather a sealant that can be applied in direct sunlight. Easy on and easy off. Last just as long as any other.
However, this summer I've used Protect-All. It's good for any surface, fiberglass, paint, metal, glass, wood, rubber, etc....
It's really easy to apply. I did my 34' tt in less than an hour. It really does a nice job. It's good for 3 to 6 months, but since it's so easy to apply that's not a big deal. I'll probably continue to use it.
Protect-All makes many different products for cleaning and maintaining your RV and I have also used their rubber roof treatment. It's also very easy to apply and made the roof look new.