There have been lots of these threads popping up lately and they are all the same. Almost everyone falls into one of two camps. There are those that bought budget rifles and feel that they need to defend what they bought when someone criticizes them; and there are those that bought more expensive rifles and feel the need to justify the cost.
The fact of the matter is that many, if not most, will never run their rifles hard enough to either realize the true capabilities of their rifles or their true limitations.
I won't go touting brands, but I will say that if you plan to run your rifle hard, get a quality rifle. What do I mean by running it hard? Well, if you plan to take carbine courses, those can be hard on a rifle. If your idea of a good time is to get together with a half a dozen of your friends and spend the weekend running drills and cooked up courses that will eat up a case and a half of ammunition, you're going to be running the rifle hard.
Being able to get through these sorts of situations is what usually separates a $700 rifle from a $900 rifle. If you ask someone about a rifle, be sure to also ask him what his opinion is based on. Ask him how many rounds he has through the rifle. If he has less than 5000 rounds through it, I seriously doubt that he can make any comments on the rifle's track record, because it really doesn't have one yet.
You do have to sort of take opinions on the web with a grain of salt. I noticed one guy in this thread giving an opinion as to what the OP should buy and unless I'm mistaken, this poster just started his own thread, not too long ago, proclaiming that he just got his first AR.
In the end, just decide how much you can spend and get the best for your money. Just remember mags and ammo. Once you do buy something, quite sweating it. Just go out and shoot it. The one thing that all ARs have in common is that they ALL break, if you shoot them enough. It's just a matter of when. The neat thing about almost all ARs is that when they do break, it's usually pretty easy to fix them, so don't burn too many brain cells on this.
If all you can afford is a Smith Sport or kit from PSA, go for it. If you have a problem, there's always the warranty and THR to fall back on.