My CBR 600 is my starter. I've ridden dirt bikes all my life, and I wouldn't suggest starting less than a 600. I think you'll get bored quick with a 250. Yeah you could get a 500 ninja, but then why not just go for the 6? Agree with Cam on not going bigger than that though. I know a few dumb fucks who thought they could get on a Hyabusa first thing...big mistake.