My favorite character is currently Lance. I think he's cool and uses dragon-type Pokemon which is a big plus for me. I don't like Tabitha that much anymore because he is way too silly (both in personality and looks) for my tastes.
N is a super well-written and interesting character, I like him a lot!
Looking to the anime, Paul is a surprisingly well-written character for a kids TV show, and he has good taste in Pokemon too.
The top tier character of the series is your BOY Guzma, god, has their ever been such a charming character in all of Pokemon? No, there hasn't. His charisma extends to all the rest of his SQUAD too!
There are so many but if I have to choose then I'll go with Lance, Elesa and Clay.
Lance was always the coolest Champion IMO, I mean he uses 3 Dragonite and Dragonite is my favorite Pokemon.
Unova has the best Gym leaders (not counting the Striaton trio) and the best of the best are Clay and Elesa. Both of them are amazing and have so much character that makes them stand out compared to the other Gym Leaders. They aren't pushovers either as their gym battles can be challenging if you aren't prepared, Volt Switch Emolga can be super annoying and Excadrill is always scary with those amazing stats.