Well let's see now; my first bike was a Suzuki 80, then a 90, then a 185, then a 360cc motocross, all of these single cylinder 2 strokes. Then I bought a 350cc four, then a 500cc thumper, then a 1000cc four that I still ride now, along with a single cylinder 250cc 4 stroke Trials bike that renders all of the street bikes totally boring. So; If you want to save yourself several decades and many thousands of dollars, just go straight to the 250cc Trials Bike !
Once you crash it countless times learning, then start to win trophies, then you can go out and buy any bike you like with complete confidence that the only thing fun about riding street is going way fast.