Kiki: Cats are my favorite animals and I've always loved black cats. She also makes me think of Kiki's Delivery Service, one of my favorite movies. I've had her in every game at some point, I believe. She's too cute (and I love her normal personality too).
Pudge: I had Pudge in m very first Wild World town. He's just always been a favorite, not sure why. I just love him. I was devastated as a kid when he moved out of my WW town and I couldn't get him to stay.
One villager who always ended up in my Animal Crossing towns was Pinky. From Wild World to Hew Horizons, she has always been in at least one of my towns lol. One villager that I have to have on all of games would probably be Punchy. I love that kitty cat so much