It comes down to some personal preferences and the type of riding you'll be doing, but I've always liked my O'Neill Reactor vest, see it
here
I think pretty much any Type III neoprene waterski vest would be what you are looking for...O'Neill, Slippery, Jet Pilot, Body Glove, Helium, Quicksilver, etc would be some brands to check out.
I was stopped once on the water, and told "that vest is not CG approved". I hopped on the swim platform, took it off, and showed the po po the markings. He said to have a nice day...