As already shared, there's a villager popularity ranking here already, but I think it's a bit outdated. Raymond is definitely in his own tier, and I think Sherb and Judy are underrated (Judy has been going for a couple of hundred NMTs lately as far as I remember).
I also think Zucker is underrated too, he should be at least Tier 2, but it's still a useful guide if you're gauging how to trade/sell/buy villagers.