Noobshooter,
First, you have to determine what you're going to use if for. Do you want a small, lightweight, close quarters gun or do you want a long distance varmint popper, or a competition gun? Since you're a new shooter, you probably don't need or want competition quality. For target shooting up to 200 yards a 16" carbine is fine, from 200 yards + I'd go with a 20" standard A4. It's a flat top so you can easily mount a scope, carry handle, or other device. The best thing about ARs is they're modular, you can use the same lower receiver and put a variety of uppers on it. Shop around, look at the different brands and note their fit, finish, materials, etc. In my opinion Colt is overpriced, there is no reason a standard A2 should cost $1200. Personally, I like Rock River Arms. If an AR can be pretty and functional, they nailed both. I bought a gently used National Match A2 and it's just incredible, I've never had a jam except when I used winchester Q3131 (cheap junk ammo). I'm not a great shot by any means but with that I can put 10 rounds under a quarter at 50 yards, not much difference at 100. Plus, the finish is almost like black satin. I've never seen another company do that. Check out the equipment exchange, AR15sales.com sells RRA lowers with "U.S. Property" markings on them. What I would do is buy a stripped lower and then get the parts kit and a buttstock of your choice put it all together (not that hard, there are instructions in the information section of this site) and then decide which upper you want to put on it. Hope my $.02 helps out a little bit, I was in your shoes not that long ago and learned some things. Take care, shoot straight. MJD