A Kawasaki badged DRZ 400. IMHO, The definitive lightweight cheap but capable dual-sport. Of the other common bikes of the genre, the KLR, DR-650, XT250, and KLX-250 ... only the KLX-250 also has a cartridge suspension that allows its long travel suspension a chance to keep up with the DRZ when the trails get rough.
There is now a wide selection of what are effectively plated dirt/race bikes, but they come with the short maintenance schedules of dirt bikes, and modern price tags.
Enough marketting :)
Another "dirt converted to street" bike has come to me. This one still has all its performance bits (FCR, cams, header, footpegs, etc). (Also rad guards and a real skid plate.)
It had a new piston and rings just a few hundred km back. I've checked the valves (in-spec), and ridden it a few kilometers.
It came to me with horrible top-end noise, which turned out to be a failed auto-decompression system, which I have removed.
As with all the dirt converted bikes I have seen, it isn't perfect. If I was keeping it, I'd fix the headlight, the mirror(s), horn, rear-tire (50% worn K270), and change the gearing to something more street suitable. Any/all of that could be done for the right buyer/price.
(p.s. Please take this off my hands before I decide to strip the performance bits and sell it with the normal street legal bits ... I don't need any more projects.)