For those of you who are purchasing your first-ever AR-15, I would highly advise you to buy a complete AR-15 from a trusted manufacturer from our list. At the very least, you should buy a total upper and possibly try to customize your own lower.
This will prevent a lot of inconveniences because you will have a full warranty on your rifle. Also, when you're just getting started, you might not know exactly what you want or need so it's best to go with a standard configuration.