lowers are lowers.
I've heard good things about Doublestar, and I have a DSArms lower and it runs just fine.
My only gripe about DSArms is their customer service and how they treat their dealers. They took 2 months to ship my lower, and they didn't give my FFL their FFL info, so we had to wait before he could keep a record of sale.
But yeah, lowers are lowers. Some just use different lower parts-kits, but I think Del-ton, DSA, and Doublestar use DPMS parts-kits.