JR (aka RDNK Gunner), Welcome to TFL. Great first post too.
Back in the day, there was... COLT. Armalite too, Then Bushmaster came along. Originally the quip was in regards ARs, "buy A, B or C" but that was then, things happen, everyone and their brother got into the AR platfform or system. Nowadays, some say Bushys... not so great, but they work. Armalite today is not ArmaLite of yesteryear, but they too work well. Colt works, but for a while people commented on pin sizes, (maybe they still do,, dunno). To me the Colt is still the baseline for comparison in terms of quality, cost, CS, etc. What is above it and what is below it and why (cost, QC, CS, etc).
So, if the above happened (and it did/does) with only three of the early mfgs, you'll always find plusses/minuses for each.
What I find ironic, is that you sir, you've BTDT and used said weapon where it counts. Maybe you should be telling us what you learned and experienced as to the pros and cons of the platform in hard use, eh?
(I kid, kinda)
Enjoy your time here at TFL. Let us know what you do end up getting, how your first build goes (photos and range report too) or an outright purchase of a complete system.
Here's my obligatory link to some eye candy, bits and pieces to be put together...