It appears that the gorillas,mice and hippos would be most ACNL players' least favorite villagers if this thread is any indication.Let's have a look then:
Gorillas:It seems that people have a size issue with the gorillas.Yeah,they're a lot bigger than a player character but it's not like we have to engage in a sumo wrestling match with them.I would think that people would be more freaked out by the gorillas' butt pads.Yep,they have butt pads,one for each cheek just like their real life inspirations.The only thing that bothers me about the gorillas is their pointy heads.You could engrave stone tablets with the tops of their heads.
Mice:The mice are 87% head and 13% body.It's amazing that they can stay upright let alone walk around.I think that the basic mouse template that Nintendo uses in their design is a lot harder to make unique than the other villagers in the game and there's what,like 37 mice in New Leaf?And those ears are huge...they have bigger ears than the elephants.
Hippos:Ok,we're talkin' big heads here(actually,enormous heads),large,flat teeth and flaring nostrils(the hippos are the Judd Nelsons of the ACNL world).If you look at the hippos on their ACNL Wiki page they don't look all that bad.Bitty is a nice addition but then you get to Harry.Wow.He kind of drags the whole species down with that fungus growing around his mouth.
Personally,I like the ducks,pigs,frogs,goats,squirrels and cats.The only species I don't like all that much are the kangaroos.I don't think they're particularly ugly or anything.They just don't interest me.