There are many options out there. I would suggest knowing what style you want and find something within that genre(sorta say). The more you get acclimated with the feel of that type of bike, the better off you will be when it comes time to upgrade. Riding a bike is riding a bike. But a lot of it is about feel, fit, and comfort. If I were to switch from a cruiser to a street bike without ever riding one, it probably wouldn't be good. And I would hate for you to learn on one type and upgrade to a different type only to drop it because you are not used to it.
You will need something with some power to keep up and have the ability to pass. Considering your size you should look around in the 650-800cc range for a beginner bike if you are gonna cruise the streets. 500cc might be just a tad too small but it should be ok for putting around the block.
A couple of examples....
Cruiser=Honda Rebel 500/ Kawasaki Vulcan S 650/ Harley Sportster 883
Street=Honda CBR 500/ Kawasaki Ninja 650/ Yamaha FZ-09