I only really know sportbikes (still have my zx-6r) so here's my input.
1. Comfort(on sportbikes) - anything but a honda(EDIT: unless its an F4i). You learn to deal with the whole "its not comfy" thing.
2. Light weight - if you're considering getting a 500, get a 600. they're accually lighter since they have all the race tech in them. but 250s are light (and ssss llll oooo wwwww) and you won't feel too bad if it falls over.
3. gravity stuff - I know how that MSF course is, with the drills and stuff. get a sportbike if you want to turn fast. doesn't matter what speed. (I can ellaborate, but I'm tired and a little tipsy)
4. smoothness - Get a fuel injected bike(smoother motor). the rest is up to you as a rider. I ride smooth if Im in town, I ride hard and rough if I want to feel like I'm nicky hayden.
it's whatever, just don't get a 1000 as your first bike. post pics when you decide.
PS. (been drinking a little tonight)