If you can find a Suzuki SV1000S, that is an excellent bike. Unfortunately, the owners usually know that too, so they can be expensive. The Honda VFR800 Interceptor is another nice bike in that class which is an excelent deal.
Beyond that, I've only read about other bikes in that class. I worked on a ZX-9 once, but all I remember was how much of a pain it was to get the spark plugs out and how tedious it was to sync the carbs. And I've never heard of the Aprilia Falco or Futura, over here Aprilias start out at 20 grand, so they're far out of the reach of some 16-year-old mechanic.
Make sure you take the bike for a ride, and look for shake in the steering head and flat spots in the power curve, as well as checking all the gears. Also remember to check for oil leaks and other obvious problems, and never accept "They all make that noise" answers. If you have a mechanics-savvy friend, bring him along.