The two I use most are M205, and Keramik, followed by Menzerna SF4000 (3500) and Ultimate Polish.
M205 I buy by the gallon. I like the consistency of the liquid, and I like the feel it creates on the paint surface as I'm polishing. I like the way it can be more or less aggressive depending on pad choice, pressure, and tool speed. I also like that I don't have to cycle the abrasives down. I can do one pass, and see where I'm at. Sometimes one or two passes with M205 is all I need, which make for a huge time and effort savings. It has done great with all the tools I've used it on - Flex PE14, Flex 3401, Porter Cable 7424, Rupes Duetto, Rupes Mini. M205 is also one of the easiest for residue wipe off, which again makes for great efficiency.
I've had one black vehicle where it just wouldn't finish down, but looking back, I may not have been aggressive enough to remove the d/a haze created by the D300/microfiber. In that case Menzerna PF2500 on LC Tangerine Hydrotech pads ended up being all I needed to complete the job.
I find that It's ridiculously easy for me to attain unreasonable levels of gloss with Menzerna SF4000. True I have to cycle the abrasives, but the finish it leaves is undeniable. Seems to be an underrated product these days, and I tend to save it for the more critical finishing jobs.
Rupes Keramik is another polish that is very easy to get great gloss. Recently learned that It's a non diminishing abrasive product (Obsessed Garage with Jason Rose sanding video), so I'll have to experiment short cycling it. On foam it does a great job cleaning up light defects, much like SF4000 (3500), but also works great with microfiber pads for more moderate defects. I get a lot of mileage from Keramik on microfiber for one step jobs. The performance, and result reminds me a lot of Menzerna SF4000. It just a bit easier to wipe off.