Bam is my favorite jock! (also my favorite villager overall tbh) He was one of my first villagers in my old town and I love that little pixel to death!
Snake and Genji seem like very popular picks, and they're my favorites as well!
Snake was one of my initial villagers when I first got the game, and at first I really didn't care for him! He slowly grew on me, until the point when he asked me to move out and I realized how much I loved him and didn't want him to leave!
I loved Genji's design, and it just so happened that he was another bunny jock villager! I like to imagine that him and Snake are good bros and go to the gym together ahah.
I really like Leonardo for whatever reason, I think he's super cute! And Stinky, he's super ugly but he grew on me a lot once he was in my town. I tried to like Genji, but couldn't. I do like Snake quite a bit, he was in my CF town.
Between the two I have (Biff and Kid Kat), I would have to say Kid Kat. Biff comes off as overly aggressive sometimes and more of a meathead. I feel like Kid Kat is someone who likes sports and exercising but doesn't take himself too seriously and just tries to have fun with it.
...I think I maybe over-analyzing this a little too much XD