City Folk for me. I was 10 when I started playing the game, and of course, had little knowledge of what to do in that game. All I wanted to do was ride the bus to go to the city!
(Though I didn't start taking Animal Crossing seriously until 2018 after picking up New Leaf and a 3DS for cheap)
Going a bit off-topic, I got hooked, and my hype for (then-newly announced) New Horizons was super strong. I really, really, REALLY wanted to play it, and actually stood in a GameStop line the morning of release day, not caring at all about what was going around at the time. The only other time I've waited in a video game-related line was to (unsuccessfully) purchase a PS5.
Unsurprisingly, some of the other men in line that had a resemblance to me were wanting
Doom Eternal, which was released on the same day. Almost all of the women in line were getting New Horizons. What was surprising, however, was that several people bought both. It's so weird considering that both games are completely different genres, but New Horizons actually won over some manly crowds later on. I even saw some art of Isabelle fighting demons with dual-wielded weapons, and Doom Guy as a player character relaxing on a sunny beach. The fact that two completely separate gamer crowds banded together as one to celebrate both games was very heartwarming.