I would have to agree with everybody else about the 250R being the best choice out of those quads you listed, however you might feel a little cramped on it since you're 6'4. If you get one you might look for one of the taller desert seats, and a handle bar riser to give you more room. You also left out the 400ex which has a little more room than the 250R and also has a lot of available mods. The Raptor handles great once you add some suspension mods, and the torquey 660 engine does well with a larger rider such as yourself. Good Luck with your decision.