Depends on if you are looking at 2stroke or 4stroke. I am going to guess 4stroke and I have a WR-450F and love the hell out of it. The things that I look at was:easy to ride,low maint(doesn't break down),Light weight,low center of gravity,Fuel capacity,Name brand(Yamaha,Honda,Kawi,Suzuki).Pay close att. to Tranny's there a few years that only have 4 speed trannys that are track bikes.Good luck.