Yes some LPKs are better than others. I've had good luck with DD and Stag. ArmaLite was all right. I didn't like DPMS or Del-Ton, both were rough.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek
The internal parts that go inside the lower receiver are one of the most important factors in determining whether you have a good AR or just a so-so AR. In fact, when it comes to AR lowers it's about the only thing that matters. Your choice of buttstock matters I guess, but not so much.
I had good luck with a Rock River LPK that I bought through Joe Bob Outfittters. The trigger parts that make contact with each other were all highly polished and that resulted in a crisp, smooth as silk trigger pull. Everything else in the LPK seemed 1st rate and went together without any issues.
__________________ Fear is a Reaction..............Courage is a Decision
I ordered 2 LPKS from Palmetto and one of them was smooth as glass the other I was not happy with . it took alot of time cleaning it up and polishing it smooth but its up to par with the other kit now. I would have to say stay with a good known manufacturer like stated above , and if you do get one thats not great they will take care of you .