Mott's is so cute! It reminds me of how actual players decorate their mayors'/residents' houses.
I don't know if I have favorites off the top of my head, but I do think that Dobie's interior is gorgeous, and Roald has a very cute interior and exterior, plus he plays KK Parade, which is one of my favorite songs
i like:
moe's. his exterior matches his fur and his interior is a doctor's office which is a little weird but it's very cute and organized good job nintendo
carmen's: i am biased i love carmen she is my favorite villager ever of all time but her exterior matches her interior and the alpine series looks good with her
tabby's: her house is so cool it's a little bath house inside
lucky's: it matches his egypt theme it's so cool
and i like the villagers who have nice houses with dark browns and have a japense style like bill and purrl but sometimes those seem like they are the same
on a side note i do not know why the wolves always have weird dirty houses like chief's and kyle's and dobie's outside are all ramshackle or dirty
I really like Stella's house, but I only have one issue with it that I also take with others. I don't like the "random" kitchens and bathrooms that are in some villager's homes. Stella has a sink in her's that kind of sticks out in a not so great way, but I
don't think it takes away the focus from her house. I just wish there was a coherent way all the villager's houses are made. For example, Marcie's house looks as realistic to a real house as you're gonna get in AC:NL, but Joey's "house" is just a beach.
I actually don't really pay attention to exteriors unless its hideous, but Lolly, Olivia, and Muffy all have beautiful interiors! I LOVE it when their houses actually look homey.
Wendy & Faunas exteriors are my favorites in the whole game ♥ I have a lot of favorites when it comes to the interior tho, so I don't know if I can give an answer. But whatever interior that looks like a living room/home.