I know it's recommended that noobs start out with a CBR250 or something along those lines, a CBR500 might not be as easy to learn and start out with but if you have taken a MSC/MSF course that will help.
Is this your first bike? If it is the Ninja 650 might be a bit much to start with. Im not saying its impossible but its important that as a new rider you get the hang of how to maneuver the bike properly and get use to riding in traffic first. Kind of a sense where you shouldnt learn how to run before walk. But if you do have some riding experience under your belt then it fine. Personally I would just stick with Honda but everyone has their own preference.
From what it sounds like the 500 would be a good starter bike. Seems like people get tired of the 250, too fast.
A lot of people last less than a year with that bike, then they feel the need to upgrade.
I hear the 650 has some kick, and would not typically be a starter bike, but more of a second bike.
Im in So*Cal, let me know when you get your bike, im usually up for a ride.
Once you are comfortable with a 250cc you get bored real fast. But you need to find other things to improve on and make use of it while you still can before moving up in engine size. The transition is different on from a 250c to 500cc or even 600cc. Depending on the bike too but once you master a 500cc or 600c you have so much more confidence on a 250cc!