Very nice parts list, Jason, good luck with your build!
I'd go along with the BCM or Daniel Defense 16" LW midlength barrel and the VTAC or Vickers padded sling. I have the VTAC and like it. Next one will be the Vickers to compare but I already know they're very similar. Do you really want the large handle on the Gunfighter CH? I love the Model 4 I got, the middle size. The large can be an advantage under a large scope, etc. but may get in the way otherwise.
I'm definitely a fan of Magpul and use the CTR and ACR buttstocks. Alsothe MBUS Gen 2 rear flip up, the MOE handguards (over a rail) and MOE pistol grip. I've stuck with the A2 birdcage but that does fly in the face of the current argument for a good comp. Which makes for a good case to stick with the 16" barrel so you can easily make changes if you find it matters to you.
I agree with most of the suppliers mentioned above. You should be able to find pretty much everything you need there. G&R Tactical is another one to check out, I've always been pleased with them.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek