The best villager is the one that doesn't ask for too many favors,doesn't load up their house with fish and bugs,doesn't move out without telling you first,isn't constantly asking to move or always changing into ugly clothing and doesn't agitate the other villagers.
Roald for me because his actions and requests made in the first week of playing made me seriously think he was majorly crushing on my mayor. This of course made me more interested in him so I did him a lot of favours, with the result he quickly achieved and continues to maintain the highest friendship with my Mayor and all other Jocks seemed a pale imitation of the glory that is Roald. I adore my chubby little Jock with his playroom style house.
I don't really know if I could pick a top favorite. I like so many...I guess Lolly or Felicity. They're both freaking adorable imo and I love cats irl too.