I trust certain companies for certain things.
Some make barrels more for my liking, while others make upper receivers/handguards that are more to my preference.
Some make great fire control parts.
Some make superior Receiver Extension Tubes.
Some make bolt carriers that do more what I want (Bootleg), but may or may not use the carrier key and fasteners I prefer.
Some make really innovative or enhanced lower receivers (ADM, LaRue, Seekins, PF, 2A, KAC, JP).
Some make excellent charge handles that don’t break.
Some make better gas systems than others with sealed gas tube-to-gas block interface (KAC, LaRue).
Precious few use actual TDP LPKs with the correct materials and spec sheet conformity, which is critical with the springs, pins, mag catch, and bolt catch.
Many make good muzzle devices, and the biggest question is whether you have brake-attach or QD suppressor interface.
Only a few make bolts that actually last under high-volume shooting. Those who adhere to the TDP in this respect do the bolt longevity a disservice by subjecting them to non-destructive testing with the HPT. Notice that KAC and the Canadians don’t do it to their 5.56 bolts, nor does AA to Grendel bolts.
Depending on the direction of the build, I’ll go down a totally different path on parts selection, which has more to do with whether it will be an extreme lightweight build, a higher performance cartridge chambering, or a DM Carbine. Will it be suppressed most of the time/always? Is it intended for an all-round SHTF/Hunting/DM set-up?
With cartridges like 6.5 Grendel or 6mm ARC, you can have a lightweight SBR or pistol that will do all of the above. Short barrel length isn’t so much of a handicap when you’re launching .450 to .615 G1 BC bullets for your distance work, while having a wide weight/construction range of heavier hunting bullets to choose from.
Some examples for direction of a buy or build might sacrifice certain things if weight, distance, or user-interface are weighted more than the others:
1. Lightweight receiver/barrel SBR or pistol. Think 2A receivers, light profile 10.5” to 12.5” barrel, light 2A matching handguard, adjustable gas carrier, quality bolt from a reputable company, TDP LPK, LaRue RET
2. One thing I have wished for over the years was for the higher-end companies to offer a builder’s kit using their quality components that the customer can select from, so that you get the same known standards from that company, but assembled your way. LaRue really knocked that one out of the park with the UU kit. You can get everything you need and order a billet LaRue lower to finish it out for a complete LaRue rifle, with choices ranging from 14 different barrel lengths and calibers, different handguard lengths, and 5 different furniture set colors.
3. For a race gun, I’m going JP or Cobalt Kinetics. Almost every part is different and for logical reasons.
4. For a high-end customer who just wants to one-stop-shop for the rifle, KAC, LaRue PredatOBR, JP, Cobalt Kinetics, Noveske, Q, TRIARC, and some others are known performers.
5. Working man blaster that will take high volume and isn’t high-brow? BCM, Colt (OEM was one of the best things they ever did.)
6. Alternate caliber like 6.5 Grendel or 6mm ARC complete build? Alex-A, Barrett, CMMG, JP, LaRue, Lone Star Armory, Precision Firearms, Seekins.