I like all the villagers I get, so I don't really have a favourite or least favourite. For example, my favourite villagers are Rocket (sisterly), Melba (normal), and Tex (smug). I never really pay notice to the personality types tbh.
It depends on which game your playing, the characters in the older games while repeating dialouge was still an issue their conversations were a lot more varied and interesting no matter the personality. Newer games however the characters are far more flanderized and uninteresting, but if I have to give my least favorite it would be the NL and NH iterations of Jock, Lazy, and Normal/Motherly. Their dialouge is the most repetitive and uninteresting out of all of them in the newer games.