Best Gym Leader: Kanto

It was really a question of Brock or Misty.

It's difficult to choose. The Kanto leaders defined the concept of a gym leader, and they had a good range of character archetypes for a Japanese 90s Game Boy RPG. The tomboy, the scientist, the traditional girl in a kimono, the ninja, the cold, stern girl, and of course, the American.

I think gym leaders nowadays should use aesthetic themes rather than strict types because it can make them very predictable and easy to beat, and it has gotten better with curveballs like multi-type Pokémon or Terrastalization, but for the most part gym leaders being mono-typed served its thematic and gameplay purpose back in the day.

As for my favourite, it's hard to pick one because I like different leaders for different reasons. I like Sabrina because she uses psychic, one of my favourite types, and I think she has a cool design and introduces a lot of interesting gen 1 weirdness to the lore regarding humans and their abilities. (Also best grill.)

I like Blane a lot because he is very distinct from the other leaders, being a much older man, and he is a scientist with implied ties to the Mewtwo project. I wish his quizzes were a little more challenging though. And I actually want to fight the trainers for the extra exp, so I get the right answers then fight them anyway.

Blue/Green is obviously the most balanced team overall, and becoming a gym leader is a good continuation of his story following gen 1. I do wonder why he didn't try for champion again after Red left.