I can't comment on the quality of the different parts, but I think AMD is run by people that used to work for Goodmark, and you can't go wrong with either, for the price.
I met Mark Headrick who started Goodmark back when he sold insurance and restored Hemicuda's for fun and bought my '71 'cuda convert from him. Super Nice guy. I remember the Gray Brothers, that I have seen on TV for AMD, used to work for Mark and it would be just like them to go off on their own. The Grays are not who I would describe as people people, but they were sticklers for quality, that is for sure.
The Gray Bros judged an AMC national event back in the 1980's and basically NOBODY got a trophy because nothing met their standards.