I don't know about Nix. He was in the perfect situation and was good but not great. Williams and Mayo both had awful coaching
Maye had skill-less receivers. I mean, most of NE thought his big receiver's name was pronounced like John Big Boutte from Buckaroo Banzai. Henry is good, but he's 3rd option good.
This may go down as the best class of QBs ever. Williams will be good, and Penix looked good in a short stint. Probably not as good at the high end as 1983 - Elway / Kelly / Marino, plus O'Brien, Eason, and Rutledge - but maybe deeper.