Looking for a four stroke or two stroke? Budget? I'd look for some KTMs. Pretty much everyone I ride with (including my dad) has KTMs, both 4stroke and 2stroke, and none of them have ever had any issues. If I was to bet money on which bikes were the most reliable, that's where I'd put my money. Personally I like 2strokes, and in that case I'd be looking for some exc/xc/xc-w 250cc, 300cc. I believe the exc has lights and all that street legal stuff, where as the xc and xc-w do not. The xc-w is the wide ratio tranny version of the xc. That option will likely depend more on what your riding, perhaps the "w" plus changing gearing would help if you plan on cruising around town on it. The 300cc version is basically the same weight as the 250cc, but faster, more torque, easier to climb up hills, etc. If you go the 4stroke route, check out their xc-w 450. They just came out with a sweet 350 4stroke, but doubt you want to spend over $7k USD on a brand new bike. I'm actually riding a suzuki rm250 now (motocross bike), and it does just fine for all the single track and technical stuff we do. Haven't had any issues with it either. Really the list could go on and on as to what bikes are decent, the above is just what I've personally rode. I don't know if there is any sand dunes or anything like that near you, but if the bike has paddle tires, I wouldn't bother with it.