I am a big time Adams' convert. But I have always had fantastic results with the 3M Swirl Remover and the 3M Ultrafina using the color coordinated 3M dimpled foam pads and my FLEX polisher. Of course it all depends on the condition of the paint you have to start with - some defects and scratches will be deep enough that there isn't really enough material surrounding the defect to safely polish away in order to smooth it out. But provided you have pretty good depth of clear coat to start with, the 3M combo has always done me right. Adams machine sealant is the absolute very best synthetic (non-carnuba) sealant/wax I have ever used. Crystal clear even under high intensity LED lighting. And the Americana Wax is just intoxicating when applied to properly prepped paint.
Oh, and the brand and type of paint really does make a huge difference with regard to which products work best. My 3M products don't do anything to the ceramic/scratch-resistant clear coat on wifey's Mercedes ML. I had to broaden my horizons and get to know the Menzerna line to properly correct that paint. And for some reason, the paint on my Green TA really responds to the Meguires Ultimate Compound and Ultimate Polish Duo.