Im getting ready to build my 1st AR-15 out of: (Basically the RRA Gov't Model without the scope/light/sight)
Complete Lower Half / NM Two Stage Trigger / 6-Position Tactical CAR Stock / Ergo Grip Black
Forged A4 Upper Receiver Assembly
SureFire M73 Tactical Rail Handguard, CAR Length
CHROME LINED Chrome Moly Barrel Assembly, 16-Inch CAR
A2 Flash Hider

Here are a some questions:

Is there anything I should consider changing?
Does an A2 flash hider need to be welded to the barrel (permanently)
Which brand do you prefer?
16" or 20" barrel (ill be shooting at around 100 yards)
Hogue grip or Ergo grip? (other?)
Heres a noob question for you, M4, A3, A2 are all types of AR-15's right? If so, whats so different with the M4, I cant really tell a difference between that and an A3.

LMT because i'm a snob

Also, 16", but without the M4 cuts. I myself have a Surfire M73 mounted, but I wish I had just spent a little extra and gotten a quality freeflot by Samson or something. The Surefire has the benefits of easy installation and removal, but given it's price level and the fact that it puts opposing pressure on the barrel/upper...

Aww Geez not another thread like this!!!!!

Build your own.

Quoted: Aww Geez not another thread like this!!!!!

100% agree.

Ok, I'll bite since I haven't seen this question a thousand times yet, and I'm fairly new so would like to help out a brother.............that said, I am not an expert!

You will be able to purcahse a complete stock gun from dealers like, GTS, Bravo, Eagle, (check out the equipment exchange site) for probably cheaper than putting together a stock gun yourself.  

If you, like I did,  want to build your own, you probably will want to upgrade parts to fit your personal needs.  things like different handguards, trigger, flash hider, grip, trigger guard, optics etc.  No point in paying for something twice.

I ended up spending way more for my weapon than one I could have bought off the shelf, but it is what I wanted.  The dealers on this site will be glad to help you out and there are no dumb questions. (I asked all of them!)

You can't go wrong with Bushmaster, RRA, or Colt. Just depends on what you like and what you can afford.  For me, I found it was easier as a first mini build, to just get a complete upper and have Bravo Co. install the hand guards and flash hider before shipping my upper to me.  I like the 16" barrel and the flash hider does not have to be pinned to make it legal like a 14.5' barrel would.   I would recommend an M4 upper with M4 feedramps.  The M4 barrel has parts of it machined thinner to reduce the weight vs a heavy all the same (well kind of) thickness barrel.

I'm getting in over my head now, but that's a start............although if you go RRA, get a 1x8 stainless steel barrel imho.....  I bought an LMT upper and put it on a RRA lower with extra goodies I put on myself......enjoy!