I have less experience than most of these guys on guitars but I have over 20 years experience on auto paint.
I echo the recommendation for Meguiar's Ultimate Compound. I've used pretty much every expensive specialist brand from Wolfgang to Swiss and everything else and quite a few of the retail stuff like Bowdens. Meguiar's is by far the easiest to work with and gives as good a result as anything else.
As for polish I never found one brand any better than the other although I used Autoglym for a very long time.
You didn't mention sealant or wax but you might consider Wolfgang Deep Gloss Sealant and the matching paint cleaner/prep which is essentially a polish so you'd do that after compounding but before waxing or sealing.
I've got it on both my cars and I've used it on a few guitar builds too. Heaps easy to use. Almost as good as those expensive ceramic coatings you get for cars these days. Throw a layer of wax on top of the sealant if you want to go the whole hog.