My advice is that you buy a 16" barreled upper (with midlength gas), and even better if you find a deal on one with a handguard you like. That's just a simple, unlikely to fail, and generally cost effective direction to take.
Building uppers, going all custom, knowing how to assemble and adjust every aspect of your AR...there's legitimate value in that. But being new, keep it simple. Those things can be part of your eventual progression.
You can get into some outstanding barreled uppers with excellent handguards for very fair prices right now. Due to the mass buying and price gauging that occurred 12-16 months ago, we now find ourselves in a buyer's market. Spike's is a solid choice. So are BCM, PSA, and various options that pop up on AIM Surplus. Whether you buy a complete upper (with BCH/CH) is up to you. There are good deals out there with or without CH/BCG. Figure out what you like and go hunting.
PSA is really tough to beat for a $700-1100 build. For my money, BCM wins in the $1000-1500 range. That recipe has yet to steer me wrong. YMMV.