Ifan is great as main character so far, he is quite classical "badass" type of guy, with snarky comments, lot of old "friends" all around the world, and is generaly conflicted person - allowing you to shape him how you like to play
Lohse is amazing companion, because she will sing you a song =)
Fane is funny as bag of badgers sometimes, and really helps with uncovering the history of Rivellon (it just feels right to have him on board).
Sebille felt great in the beginning, I dont really like her late development, but its just my personal taste (she came back to classical elven cliches)
I have beast in my party.. aaand he is quite boring to be honest. Nothing interesting really comes to my mind with him.
Cant comment on Red Prince, as I don´t have him in party, I am planning to have him as player character in "badass villain" walkthrough.
