In my current town my least favorite is Olaf. I like anteaters but I just don't like him. First off he had the nerve to build his house directly in front of mine. For real? Like I want to be staring at the back of his house all day. Geez. Then he makes a comment to me yesterday about how I'm always staring at him or something. I wish I could kick him out of town for that!
My least favorite villager of all time though is Gaston!!! I hate his face and his attitude and he's just such a nasty little rabbit. If he comes to my village I tend to keep him around just so I can hit him with my net and piss him off. Lol