I've used SSR 3, 2.5, 1, Z-PC, Menzerna IP/FPII and Optimum Polish and Compound. My favorites right now are the Optimum products mainly because they don't dust and have a really long working time, and because the polish alone can be used on most cars solo - just use a cutting pad to remove marks, and a polishing pad to get your finish LSP ready. The compound will take out heavy swirls on a cutting pad (although not quite as well as SSR3) but doesn't haze nearly as much, and looks awesome followed by the polish. Just my $0.02.