I have been browsing many websites, and weighing many options. I am looking for help, or suggestions on a complete upper. The things I am looking for in an upper are:
M4 feedramps
18-20" bbl
Threaded barrel
Forward assist
Low pro gas block
Minimum 10" handguard
No carry handle/flat top
ETI 1:7 or 1:8 twist
$600-$900
Any suggestions would be welcomed. Primarily using this upper for 100-200 yard target practice. Occasionally visiting a 600 yard range, and would like to be able to use this there also. Going on a pas lower that I've built with above average quality parts. Thanks in advance!

Why not build?  With those specifications you could build a helluva upper with that budget.

I guess I just fear the unknown... I also don't have any tools for it. I would like to be shooting this thing in the next few weeks.

I hear you.  Bravo Co has 20" uppers in the mid-$600 range.  Without a rail, it's $440.  Hard to beat.  I think it'll be hard to find an 18" upper with a 1:7 twist.  I have no doubt they exist, but what I am seeing nowadays is a proliferation of the 1:8 .223 Wylde barrel, which is an awesome barrel.  You can find a .223 Wylde upper for the mid-$500s on up.

Take a look at JSE Surplus.  They have quite a few 18-20" Wylde uppers.

Great recommendation. You can always buy everything and have someone else(like ADCO) assemble it for you. ADCO is super fast, you'll get exactly what you want with no compromise, will probably end up being less expensive(if you know how to shop, try the EE for rail, upper, GB) and it will be uniquely yours. I'd go this route.

Why are you wanting a 18-20" barrel rather than a 16"?

Thanks for all the suggestions! I had never checked out JSE Surplus before. I am looking for a 18-20" because I already have a 14.5 with an aim point and piggy brake that I love, now I want something totally different.