The GSX650 seems to be the bastard of the bunch.
The SV was THE 650 to have for the last decade or so, the aftermarket is there and the parts compatibility with its SS bog brothers is there for some parts.
The Ninja 650 seems to be the up and comer, not better than the sv at anything, but it is a slightly newer design. It seems to be an overall well rounded bike and would serve you well.
Another bike you might want to include is the often looked over FZ6r from yamaha. Its sort of forgotten amongst its class, but really can easily hold its own weather its railing through corners or cruising on the highway.
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