Based on what? How many of each have you compared? By what standard or test did you determine that one part was of higher quality than another? Please include examples of where DPMS parts failed when a part from another company would not have failed?
Several dozen builds. Had to use DPMS kits when I couldn't source STAG, RRA LPKs. Of those, had to use DPMS kits 6 times. Had issues with about half dozen springs among the half dozen kits. Every single one of the DPMS kits had poorly finished parts, with burrs, or out of spec parts that required ridiculous amounts of post-sale fitting and polishing just to get them to fit together in somewhat semblance of proper fit/function. I ended up completely stripping two lowers with DPMS kits and replacing them with a RRA & a STAG LPK. No issues thereafter.
Haven't had a single issue with the dozen and half other builds I've done using either STAG or RRA LPKs. Incidentally, I had a couple dozen brand new DPMS mags that weren't worth a damn either. They were new production, new anti-tilt followers, were properly pinned and wouldn't feed worth a damn. I sold them at a loss to a buddy who knew what he was getting and bought LAR-15 & P-Mags. Zero issues.
Obviously you own a DPMS rifle, otherwise you wouldn't have your back up or your nose bent out of shape. Whatever floats your boat. I've had nothing but issues or problems with the DPMS products that I've used. Speaking with a number of other fellow shooters, I've learned that my experience isn't unique or isolated.
That said, if you are happy with your DPMS rifle, I'm glad! The more AR-15 owners we have the better it is for all of us other black rifle owner. There was nothing personal intended. I merely offered an opinion based on what I think was a decent amount of experience related to the topic under discussion. STAG generally makes good stuff, although even they have slip-ups in QC, just like any manufacturer.