The main differences are the looks and the rider position. It is important to get the one that feels best. If you put looks first, you will end up with a bike that you sit and admire much more than you ride.
As for a first bike, the Triumph twins are the only bikes over 400CC that I feel behave well enough for a first time rider.
Some new rider tips:
1. Take the MSF new rider safety course! This is important!
2. Think about riding when you ride. If you think about crashing, you probably will.
3. Always look where you want to go. Never look at what you want to avoid any longer than you need to to see where it is. This is because you always automatically steer to where you are looking.
