Ok. I’m uncertain if the op is new to building an at or new to the ar15 platform.
Since you wanted a parts list, this is what I would suggest to anyone not looking for Gucci, but wanting a great product. I use all these parts on rifles although not all on the same rifle.

upper:
Aero precision
Any mil-spec upper parts kit
Faxon 16” match gunner profile barrel mid length
Vg6 gamma compensator
15” Midwest industries slim m-lok Handguard
Steel low profile gas block
Mid length gas tube /w roll pin

Lower:
Aero ar15 lower
Cmmg lower parts kit
Milspec buffer tube kit (tube, spring, buffer, endplate)
Mil-spec Magpul moe grip and stock.
P-mags.


Whatever sights you want. There are literally tons of options here.
Iron sights = magpul pro flip up iron set
Red dot= aimpoint and trijicon if you don’t mind spending a little money
Lpvo= strike eagle, primary arms
Scope= Leupold.

I would stick with reputable companies like Primary arms, palmetto state armory, joebob outfitters just to name a few.
Of course, all of this is just my opinion. Good luck with your adventure