my first bike was an fzr600. Good starter bikes, i wouldnt mind finding a clean 250 or 400 to ride again.
Just take it slow till you feel comfortable, dress for the crash not the ride.
Personally i would rather ride supermotos or v-twin sport bikes than any other bike, but thats just personaly preference (tl1000r, busa, zx14, choppers,pretty much every kind of harley, 600's, 1000's, jap cruisers--rode all these but supermoto is too much fun on the rode not to ride one)
also my buddy's first bike was an 07? R6-so if not if a 600 is too much, its if you dont push yourself beyond your experience
DRZ400 for sales plus if you low side a SM your only item to repair is a bar end.