There are too many variables...which polisher to buy. Are you a pro or a beginner? How kind of work are you looking at doing- significant paint correction or, primarily, polishing? I have a Porter and it's fine; but then I do family cars on the weekend. Depending on the product and pad I can do some paint correction. Considering the price of the units and the work that I do, a Flex is a little pricey. If I went, "pro" I'd buy a Flex because it will do more...faster. Can't comment on the other models. Good luck, Auto Detailing is awesome.