Wasting your time.
No best polish as such. Srp and LP are pre cleaners, both have abrasives in them. But, SRP is ful of fillers, so will hide the marring. I have both, and SRP i think is easier to use, as you can run round the whole car quickly by hand and then buff off by hand. LP requires a lot more work, and the abrasives need working down. I use LP by machine now and again but not by hand.
Id top one of the two off with a sealant or wax as LP and srp provide little protection (if any).