I'd say the Toyota of bikes has gotta be Honda. Hands down the most reliable and well engineered (Jap) bikes period. Then it'd be Yamaha a close second 
Trail bike do it all XR 400 hands down. My favorite bike I ever owned.
General consensus seems to be honda! All I gotta say is
to honda. New or old, they engineer them really well, and I can't remember one ever leaving me stranded.
XRs are very well built, but they're not race bikes! IF you take it to the track, you're lucky to only break shock parts, and if you jump a lot it's gonna break the frame.
If you're thinking trail bike, kawasaki kdx175-200 are great bikes, and are a dirt simple air cooled bike. A similar bike, but harder to snatch up, are the old yamaha it175-200, but I'd lean toward the it200 since it has a disc front brake.
Your question is really open ended too, so if you tell us more about what you want it for, I'm sure we can give you some more specifics. Your size may make a difference also.
