either Rebel is fantastic. Just depends on what kind of riding you want to do. 300 for the city absolutely. Which is what I had. The 500 for city/highway.
The 300 is certainly capable of highway speeds, but you won't like the headwind or the comfort much. Which is one of the reason why I sold my rebel. I should of gotten the 500 when I first got the bike, but I got a good upgrade. I'll still miss the Rebel though, it was my first bike.