Well first off, I may as well jump on the Lillie bandwagon, and everyone else here explains why she's awesome better than I ever could. Next up would probably be Nanu, if not purely for his 'I dont care' Attitude towards pretty much everything Acerola, Guzma and Lusamine also deserve special Mentions, Acerola just for being so darn adorbs, Guzma for his character development near the end of the game, and Lusamine for being one scary woman
I terms of all character, yes it was lillie. In terms of Rivals, Gladion. While he is a total edgelord, he had a noble purpose while still being awesome in my opinion. He actually reminded me of one of my philosophies: One can only posses that which they can protect. He wanted to protect his family and for him the journey wasn't about finding the strength but learning how to use it. While he didn't have as much character development as Lillie did, I still enjoy his story a lot more.
I also really liked Gladion in the story. He was a good and more fleshed out character, being an awesome rival but still a person who wants to do some good. His design is cool too!
I have to say Guzma is my favorite, simply because he comes off as a really relatable villain. His whole character arc is awesome, as well as visual design. So, I gotta give props to my boy Big G!
I think my favorite would have to be Hau and Mallow. Mallow is so beautifully bubbly and cheerful, she's giving everything she has and it just suits her wonderfully. I love how she cooks and wants to impress her friends and her Kahuna, and just her overall spunk makes me smile. Hau is always a smile, I'm so glad he's in the game. He loves Pokémon so much and is trying to find his place in the world, and really, aren't we all? Lusamine is an excellent villain, she gives me the heebie-jeebies! But I know people that delusional and control-freak, so it hits kinda close to home.
I found Acerola to be a bundle of joy. Normally, I’m repelled by the overly optermistic game characters, but Team Skull’s pokenapping gave some more depth to her character than most games allow.
Guzma for life, he is an awesome character, and didn't go sudden soft in the end, he keeps his badass character. and now I think about it, I hope to see him soon in US.
Guzma or Ilima! I know Guzma is a super cliche character to like, but oh well. He has stolen my heart. I really like Ilima's color scheme for some reason.
A decent part of me wants to say Hau. I believe it's because he has so many qualities that he shares with my favourite Pokémon rival, Barry. Hau isn't just a typical "friendly" rival kind of guy that's friendly for the sake of. He has actual goals that he wants to attain as a Trainer, which include attempting to best you in battle. He's friendly without losing competitive touch and I think that's an important balance to strike that Game Freak has had trouble with especially in XY.
I would have to say Gladion, even though he worked with Team Skull, he still worked with us to help save Cosmog. (And I loved it when he gave us a Type: Null)
Mina, because I like her design and personality, and she specialises in one of my favourite types, Fairy. Lillie and Nanu are also favourites of mine.
I honestly hate most of gen 7's characters, but if i had to pick one I like, it would be Kukui. The man is chill, and I can appreciate that type of attitude towards life. Also, his character design is pretty good.
You must have only played USUM. In the original, character development was a thing and the plot wasn't confusing and boring for most of the game.
My favorite character would probably have to be Gladion. I say probably because there's so many great characters to choose from (Guzma and Lillie come to mind) that it's hard to narrow it down to a single person. I have a weird liking for edgelords, and Gladion is one of the biggest edgelords, if not THE biggest edgelord in the series. His backstory is also very interesting to me. Like Lillie, he stole a Pokémon from the Aether Foundation and ran away. This Pokémon of course being Type: Null. I just find him to be an interesting character and his resolution with his mother and him Spoiler going to Kanto just made him even more likeable for me.
No, ironically UM is the gen 7 game I have yet to complete. I've played S/M and hated them in that, they may have had character development but that doesn't mean it was good.
Has Lillie been said yet? Gotta go with the big bad boss, ya boy Guzma. He's just a good old thug. He also has the best theme music.