I was in the same boat 2.5 years ago...
For my first build, I opted for a 'kit' from Delton, which was really a completely assembled upper, with a stock and a LPK. I wanted to make sure the head spacing was done by someone who was trained, and didn't want to buy the block to hold the upper in a vice.
I picked up the stripped lower and the rest is history.
With all the detailed instructions, with pics of each step available on the web, putting together a lower was not difficult at all. I didn't even purchased a multi-tool and I already had punches.
The rifle has been 100% reliable for my purposes (target shooting on the range and plinking in the gravel pit) and is very accurate. The whole gig (with mags) cost me about $650.
Is it the "best" ... no, far from it. But then again, I am not an LEO, whose life may depend on his patrol rifle. Some day when I'm rich and hopefully not famous, I'll build another with hand picked parts. But as of today, I have no regrets with my decision.
Read up on the AR15.com articles and see what you think your really need.
If you're not interested in dropping ~$500 on an optic, I would suggest saving some money and getting an A1 or A2 upper, rather than purchasing an A3 upper and then having to buy a DCH or BIS, as the traditional AR sights are excellent.
I would also suggest getting a middy, but will let you read up on that and convince yourself.
Whether you drop $600 or $1,200, you are going to love having an AR.
What I find amusing is when guys pump >$1k into their AR and then pick up a CMMG 22 conversion kit and that's all they shoot with it.