The very last type of seat cover I would consider would be any that are made from neoprene like Wet Okole's are. Neoprene is not waterproof and it even soaks up perspiration. And if the seats get rained on or something spills without you wiping the neoprene off quickly, it will soak into the neoprene and take days to dry out. and the colored nylon covers that they offer fade quickly and unevenly when exposed to the sun. Black becomes purple, red becomes pink, etc.
Personally, I've had two sets of Bestop's seat covers (two different TJs) and like them a lot.