[gringolet]

It seems the Rock River AR lowers are the most sought after...
I am just wondering why/how they are considered superior to the others?

[cbsbyte]

Stag Arms is the AR line made in house by CMT Machining in New Britain CT. CMT also makes parts including the lowers for RRA and a few other companies. Bushmaster lowers might be made by CMT though I am not sure about that.

[Jackal]

All good. Kinda like comparing apples to apples. Same thing built on the same machinery for slightly different prices. Go for whichever of those 3 that is the cheapest.