Eugene: I picked him way before NH was even announced. My friend group on Discord basically treats him like the AC version of one friend's OC, who is the best friend of
my OC who I'm going to create as a human villagers... whenever I get around to it.
Alice: Same reason but with my OC

And she was just so freaking cute in Pocket Camp. Alice is love.
Raddle: Miles island villager I invited because I placed all three homes in one day and then found out they're going to be randomly filled. Cute design, and I wanted a frog anyway, so why not? Turned out I forgot how absolutely amazing lazy frogs are (I had Jeremiah in my first NL town and LOVED him) He'll stay forever. Kinda glad he has a tutorial house too.
Peanut: Caught my attention when she was camping in my NL town, met her on the first mystery island, felt like fate. I was okay with replacing her with a peppy I like more later, but there really isn't one. Except for Bunnie who falls under the no repeat rule.
Nan: I was tired and had to take someone, and she was reasonably cute. I don't think I ever fell in love with a villager this fast. Unfortunately this means no room for other great nirmals, but there's no way I'll ever get rid of my girl.
Bree: I was in the mood for island hopping and decided to take the first villager I didn't dislike. Same as with Peanut - there just aren't any snooties I like more, just one I alteady had in NL.
Fuchsia: I don't like most sisterly designs, the only ones I didn't have were Fuchsia and Pashmina. Fuchsia won because she's not a duplicate species and she makes a good third for the "character-based" group, and her house fits nicely into my village.
Raymond: Remember the OC I mentioned? She's an IT and security manager, and she needs employees. And his house just so happens to have the same exterior as Eugene's, AND they fit an unrelated design idea, so that was a no brainer really.
Avery: I do not like what they did to the crankies in this game. They aren't cranky. They're barely anything other that absurdly confused, which is why I almost skipped them. But I took a look at the list and realized Avery looked unusual enough to... Not really be a villager, but an island god. One who does not understand what these people are doing here all of a sudden, but he's trying to roll with it. (Octavian as an alien was a similar idea, but it didn't fit as well, and his exterior would have clashed since I originally wanted to keep the asian themed part for Genji.)
Sterling: Yeah... This one was hard. I just love Genji that much and it took a while (and a post telling me how much he was downgraded compatred to NL) to settle on the duplicate eagle. The idea came from a post on Gamefaqs stating how underrated he is because his design is so unique. I realized that he would be the perfect town guard for the town I'm planning. Sucks a little that he'll live close to other villagers, but the story potential is too good to pass up.