I loved the KLR650! Awesome for anyone 6+":
A couple of negative points, but not that many.
The Honda NC700s is just another beauty for 5'8" people, however I felt like my knees where hitting the gas tank due to being too large:
Surprisingly the tad smaller CB500x sits better for tall people, but doesn't have as large storage tank:
The good about this bike is that it has a large gas tank, good to get you going for many miles (If I'm correct over 250-300 miles per tank).
If you're more old school, I can't really help you; I'm not old school.
As a tall person I was surprised at how well the newer Honda Rebel 250s sat:
A small modification necessary on the handlebars so they won't hit the knees of a tall person (just tilting them more up), and a tall person would be ready to go.
Their suspension was softer than many bikes of that caliber, and their seat felt like an air compression seat (with a tiny hole in the seat, so when you sat, you didn't immediately sank down, until the air had left the seat; some kind of extra cushioning that seems to work perfectly well!
They have a slightly larger fuel injected bike, the RS750, I sat on that too, and it feels as tiny as a 750 bike can get, not to mention Honda quality and fuel injection, means MPG monster:
A parallel twin engine makes both on the Rebel, and the RS750, for a cheaper, more efficient, and smaller bike, with higher top speeds, than on the VT750.
They're the eco versions of the VT750 or the Honda Shadow or Aero bikes. The shadow or aero bikes look like larger bikes (look like 1200cc bikes), because of the V-twin cylinder layout, but don't handle as well, due to being so large.
I sat on the TU250x and it sat a bit odd for a tall person like me, but it is perfectly possible to get accustomed to it.
These tiny bikes feel silly when you're tall, but they sure as ride fun! The only thing I didn't like is that the handlebars where in the way of my knees a lot, and needed at least 2" riser pieces.
I did not try racing bikes, as I think those bikes are for hooligans, and don't want to be associated with such; besides they get stolen more often; much like a Honda Accord or Civic used to be owned by idiots who try to pimp their $500 second hand cars like crazy, that are falling apart, and I just pass them with my Chevy Cruze Eco car, as if they where snails on the road.
Dunno, I think a sports bike does not belong on the roads, it's uncomfortable, almost impossible to ride long rides on, and people owning them usually only have them to speed with them; not to slowly enjoy the ride, taking in the environment, or adventuring.