I switched from conventional wax (fan of Colinite products) to polymers over 10 yrs ago. I've tried lots from high end $ to NuFinish (reasonable price & availability) on boat, car & motorhome and found little difference...always came back to NuFinish... EZ on & off w good water beading & durability.
I've recently started experimenting w DIY ceramic/ graphene coatings and so far like the performance & ease of use... very EZ on/off.
I dont care what I/ you use... the shine performance is in the prep NOT the protective coating. I will use a mild polish or swirl remover w foam cutting pad on a dual action polisher for prep. Only way to tell if and how aggressive a polish you need is to do a little experimenting on small panels/sections.
I have tried 303 Graphene coating on car & boat and liked it on car / paint but didn't see much difference on gel coat. I also tried Turtle Wax Hybrid Ceramic/wax Coating and so far (car only) like it's ease of use... light spray & wipe & polish w microfiber. That is my new #1 recommendation but sure there are other equals out there. Many of the new ceramic coatings are very fussy w prep & environmental conditions for application & "curing". I have to work outside and sometimes in sun and found the 303 Graphene & Turtle Hybrid rather forgiving even in sun.
Good comment re boat paints above... my hull is painted w Awlcraft & mfg (obviously) recommends only hand applying their products. Their protective coating is a polymer and I've used it, NuFinish and other and don't see much difference as the hull doesn't see much direct sun.
Epilog... getting older I've looked for help / pro to do boat polish. My go to friend & his wife quit doing boat detailing ( samecreason getting older, retired & now Gkids. Hired a new young guy based on boat neighbor recommendation and took advantage of pre- pay discount... big mistake... no show on sched 1st day, got in a half day and never returned... ghosted me and wouldn't return calls. After 5 mos, court appearance and having wages garnished finally got my $ back.
DO NOT EVER PRE PAY!