My first bike EVER was (is ) a '99 Monster 750. I've had it for almost two years now, and still haven't ridden it to it's full potential yet. Its got plenty of oomph, and can keep up with bigger bikes if need be. Plenty of torque too. In the twisties you can just leave it in third and go just as fast as any sane person would want. Very forgiving, and plenty capable of covering my ass if I do something stupid.
It was under $3k, insurance is reasonable, even for a new rider.Like others have said, wear proper gear, and ride your own ride.
Good luck with which ever bike you choose... ride safe! [moto]