Some suggestions:
Barrel: Ballistic Advantage Hanson profile or Faxon Gunner profiles are my favorite check them out.
Muzzle devise: VG6 (part of Aero Precision) best performance / value IMO.
Safety: Radian Talon, again best performance / value.
Handgaurds: I typically go with the Aero Precision M4E1 with the Gen 2 M-lok as there attachment design is super rigid but for a normal upper I like the Texas company STNGR. They are a good performance / value option as well as Midwest Industries (Combat rail).
Stocks / grips: Magpul makes everything one could need / want, I’ve never found a different company’s products that would cause me to switch.
Optics: Primary Arms ACSS reticle options have been great for me, give them a look, your going to need glass right?
Sounds like you have a great build shaping up and hope this helps a bit. Don’t worry, after you get this one built you’ll think of some things you want to change and end up building a dozen...
They are like potato chips
This is the best site for info, be sure to check out the build guides and welcome aboard.
ETA: There are so many vendors out there it can be overwhelming. This is my GTG vendor list:
Primary Arms (optics, parts)
Schuyler Arms (builder sets, everything Aero)
Arm or Ally ( barrels, bcg)
Right to Bear ( barrels, bcg)
Wing Tactical ( specialty items)
WC Armory ( bcg )
Palmetto State Armory ( for certain deals)