I feel like the more well-liked villagers have designs that are simple yet distinct, overly generic villagers and overly complicated villagers tend to both get overlooked. A very simple face with a pleasing but not overwhelming colour palette seems to do the trick for most. For me though, I actually tend to like the really over-complicated villagers, so I end up liking villagers like Moose or other villagers that a lot of people tend to dislike because they are sort of weird.