They were. At the time they were the only source for the TDP, as they owned the rights to it. FN got copies to produce their .mil rifles but were prohibited from using it on their commercial guns. Companies like LMT , BCM, And Sabre Defense (gone tits up) basically made guns to TDP spec because it was no great secret in how most of the recipe was formulated.they are, or were the main contracted supplier for the us military for most AR15 based weapon systems. .. they are the standard that all the other companies have had to improve upon.
they suck at aesthetics, but as far as quality where it matters: barrels, BCGs, Recievers... second to none.
Colt is and has been the gold standard for a baseline AR and AR components. Correct Materials, Maching, QC and Batch testing is why COLT small parts always sell for a premium. Today, BCM puts out as good if not a better product, same with KAC. Noveske hasn't done bubblegum since John died, and DD despite some of the contract awards, is still not the quality of BCM. LMT is up there too, but they havent inovated much outside the MARS system.
For out of the box AR you just can't beat a SR15. Mod 0, 1 or 2.
Been building AR's for over 20 years professionally, in the military and as a hobby and you can't build as gun as accurate, reliable, durable and most of all, repeatable as the SR15. Its an easy choice.