It all depends on what you prefer. Would you rather have something with a hell of a lot more speed, or something slow and for trails. It's hard to even compare the two because the are so far apart. I had a yz85 when I was younger and it was a real fun bike, but very sketchy for speed to weight ratio. haha! the 100's are verrrry slow, but they'll run forever. My buddy has one and it's fun to mess around on, but the shocks suck, not fast, and not all that well through trails either. I would take the 85, but I also prefer speed over reliablity.