What is the best motorcycle to start on?

I have been wanting a motorcycle ever since i can remember, I'm finally going to purchase one upon return from my deployment. I just don't know what the best type of bike to buy is. My stepfather made me an offer on an 04 or 05 nighttrain (which just found out isn't all that much heavier than a sportster), been looking at sportsters but they just don't jump out at me (but if it's best to learn on, will buy and ride for a year or so), and have been looking at the CBR 600 and GSX-R 600/750. I'm 5'11 and 190-195lbs, and don't have a lot of riding experiance. I plan on taking a motorcycle course, one for the simple fact to have a good feel for them before I go riding all over the place... and two it's required by the Army. Any input or suggestions on a different bike if these are bad ideas would be greatly appreciated.