Who makes the best and most reliable? Are they as good as the old saiga 12?

Saiga

I've had fairly good luck with my KUSA KS-12 aside from the usual need for break in.  I did have a "tactical tuning" done by Dissident Arms (extremely slow work but good), but that was choice not necessity.  One of my motivations for going US built was the warranty and serviceability standpoint.  I just didn't want the hassle of trying to get an importer to deal with any problems.  Whichever you use, get csspecs steel Saiga mags, most others are junk.