Yamaha 490, XRHonda's hold up the best and you won't out grow them. I heard KTM has it's issues. BMW is a heavy pig, stay light as possible with the dirt side.
I use to ride 600's all the time, I'm 6'03" @300, I'll be looking at the Yamaha.
BTW, Kawi and Suzi's were pure crap compared to the...