Suzuki DR-Z400SM. Perfect bike. Seriously.
Good luck finding Rebel 450s as they were only made for a few years back in the 80s. DR200SE is not bad. Virago 250 is still being produced but it is now called the V-Star 250. Other good bikes to consider:
Kawasaki Vulcan 500 LTD
Kawasaki Super Sherpa (a 250cc dual sport)
Honda Nighthawk 250 (no longer in production as of this year but should be tons on the used market)
Older pre-fairing Suzuki GS500s, like 2004 and older.