Some characters I loved, some I hated... but I guess I will find something to say about every single one of them. Going to list them from best to worst in my opinion. ^^
I voted for Vaeril, because of the whole fallen druid thing. Characters struggling with dark powers they are not supposed to have are always my cup of tea. Also Vaeril always acts so kind and calm despite his powers and at the same time stays perfectly reserved. He is one of the characters I have the easiest time to get along with.
Second place might be Kusho. (The only character in this game where I really think it's a shame he's not romancable :,D)
I like his attentive nature and him being so honest, almost brash at times, yet never completely letting go of that mysterious part of him.
(And I really had to laugh about that scene with Myrth. Omg.

)
While I like both Enok and Sylrissa for their funny dialogues... I have to say Enok wins this match. Him always being after the finest of cooking ingredients... it made me laugh so much.

Also it makes him strangely adorable. :3
Jasper's philosophical questions also are something I'm very fond of.
Galan and Dasyra are incredibly well written. I love how they contrast each other (Galan trying to become calmer and Dasyra finding out she needs excitement in her life) and share their personal development with the MC.
Larik is my bro.
Karen and Apolimesho fit neatly into the story as mentors and are - as always - pretty interesting characters. ^^
That being said: I'd love to see a game someday about Apolimesho's younger days.
Zachary and Valery... hands down - I love them as the crazy vampires they are.
Cedric has some interesting things to tell... but that's it about him.
Thomas... I don't know... I always smile when he appears. I guess that means I like him. Or is it his grumpy face?
Nuala is very well written. No doubt about that. But something about her makes me feel uneasy. Could be that I see too much of me in her... so as character I like her, but not as romance option.
Senya... well... she's good I guess. She had too little screentime though to make me feel one way or the other about her.
Leena I greatly dislike. She's all about being tough and even though there are scenes where she's showing her soft side - they fail to change my mind about her. Mostly maybe because I find the whole amazon culture exhaustingly annoying.
(Except the griffons. The griffons are cute. :3)
And lastly there is Geraldine... omg... I don't know - I just hate her and her opinions.