I've been riding a Kawasaki Ninja 250r for the past 4 months and I'm getting the upgrade itch. There are so many options, I could really use some advice on choosing a good second bike. I'm 20, taken the safety course, and I would call myself a responsible rider. I like the Kawasaki Ninja 650, ZX-6R, Suzuki SV650,Yamaha YZF-R6, Honda CBR600RR, or maybe even the Honda CBR1000RR. I'm open to hearing any other suggestions as well. Thanks in advance.