I haven't actually seen a lot of villager interiors, but I agree about Marshal's and Julian's. Marshal's interior in particular struck me, and not just because he's my favorite villager of all time. His house in New Leaf is pretty meh, it even has sloppy furniture in it. In New Horizons, though...my smug squirrel boi went full class. His furniture just gives off a strong aura of sophistication that I love.
Poppy's is my favorite that I've seen so far. If she ever ends up on my island, I don't know if I'd be able to let her go. I want to stay in her house forever. lol Really want that campfire with marshmallows furniture.
Elvis. omg, his house is a palace and he is a king. I was super surprised when I went to greet him and he looked like royalty. His aesthetic is fantastic!
Marshal's or Julian's. Marshal's interior is more on the modern side and I like the cafe vibes you get in there!
Julian's obviously is zodiac themed so its it's pretty!!
Savannah has a really nice house, it's probably my favorite so far. After I saw it, I completely changed my plans for decorating the main area of my island.
Freya had a beautiful exterior. I got her as a random move in and didn't want to keep her, but I actually considered it briefly just because I loved her exterior so much.