Proflex Bright White Caulk

i usually buy 3M white polyurethane, thats the original all these others are based

the marine grade is also a permanent adhesive, used to mount deck cleats on boats for tying up at the dock, not to be used where you might want to remove it, like sealing roof vents to the roof

i stick to the 3M regular white polyurethane

I prefer Dicor. It doesn't yellow or get as hard as the clear Proflex they slathered and slopped all over my Arctic Fox. At least solvent breaks it down enough to get some of the stuff off that's a result of their finger painting around lights.

For an RV Dicor is still the best. Yes, it's a lot more expensive than what's sold at the big box home self-improvement stores, but it is made for RV use.

I've had good luck with Dicor products. Mostly, the self leveling LAP sealant.