Budsmopker..

how tall are you
do you already ride
do you have a lot of upper body strength

Crotch rockets are the cat's ass but if it's your first bike stick to one that has like NO power in low RPMs so you can learn on it. Even the 600s that are being made now are fucking nasty machines!! The ninja 250 is just about a perfect starter bike; it's cheap, ($~3000 US) light, indestructible (same engine since 1986!!! if it ain't broke... lol), and while it is really predictable in the low rpms, it will DEFINITELY snap your neck back when you hit the big 9000!!!! wOOt. It's a sick little bike that is very very maneuverable and corners like a dream. My friends with much bigger bikes have FINALLY gotten used to seeing me lay the footpegs down in turns. lol it used to scare the shit out of them, they thought I was going to bite it.
But I'm looking at a CBR 600 f4i as soon as I stop being a broke bitch.