thumper question klx,wr,yzf,xr,dr

Hey,
The YZF is a race bike, highly tuned, but needs more maintenance. The WR is basically the same as the YZF setup for woods/trails. The rest of the bikes you mentioned are the "play" trail bikes. In general, they will be more reliable (less tuned), with less maintenance.
When the new Yamaha's thumpers came out, they became wildly popular. Everybody bought one, except me, so you will see alot of them. The other bikes have been around for a while, but in general, were never as popular as the Honda XR's.
I've always been a Honda nut, and XR's have always fit my needs perfectly. If you are confident you can handle an XR250, then I would suggest looking at an XR400. Roughly the same bike, just a little heavier and a good bit more power. You should be able to find plenty of 400's. As a second choice I would look at a KLX 300, if you can find one. Great handling, good power, very dependable. I've never been a fan of Suzuki, but they did a good job with the DRZ 400's. Good luck.

The XR's are fine trailbikes and are extremely reliable. They are a bit heavy and underpowered, but they are the kings of tight nasty, slippery conditions. the KLX is a more modern design with liquid, cooling and better suspension and great handling and a bit better power than the XR250. Hop-up shops can make the KLX or the XR run very strong. KLX owners tend to keep their bikes for a long time. There are onl 2 problems with the KLX, thye have a brittle kickstart idler gear and they can be finicky to start. I currently am the owner of my 4th KLX and would recommend them to anyone. I keep trying other bikes, but I always come back to the KLX. Since i just installed a thumper-racing 340 kit in my current bike, I feel it is the perfect bike for me. You cannot go wrong with either the XR or the KLX, they are both fine playbikes, the KLX can just be a better racer if you like.