I have used a few different plastic cleaning kits from automotive stores but keep coming back to Novus.
Novus 1 is perfect for a quick clean and shine, Novus 2 gets out deeper marks and minor scuffs (cleans the black from my holster off the ABS nicely.
Novus 3 I have only used on a couple of really tough scuffs, but followed it up with the Novus 2 then Shine with 1.