Guzma is definitely my favorite. He kinda respects you as a trainer, yet at the same time, he wants to defeat you in a battle at all costs. Plus he's passionate about bug Pokémon.
(insert lillie or guzma here for bangwagon) I personally loved Ilima a lot! He's just a super pretty character, he may have had a small to minimal role in the story but he seems like a pretty cool guy. not the mention all the pretty fanart of him