For me, favourite characters I liked were:
Sis
Mina
Darcy (I actually quite liked his joking nature, and I just love the photoshopped picture in your safehouse!)
Heck
Omen (cool professional)
Favourite characters I hate (as in, brilliant characters that really made you hate them):
Leland
Marburg (haven't managed to kill him yet, but his smugness made me immediately dislike him)
Brayko (I spared him first playthrough since I realised I had been set up, not again though)
Award for character that grew on me after initial disinterest:
Scarlet, wasn't too impressed with her but gave her a chance since she was a redhead, and her personality grew on me, and the twist! Second playthrough I also took the suave approach on the plane and her eyerolling when you tell her you're a spy is just lolworthy (and one of the best conveyance of emotion via character expression in a game I have seen for a while).
Most boring character award:
Madison, sorry but she seemed geared up to die pitifully and that's it, and so I let her fulfill her role and, well, die pitifully. Was meh to her, the worse response you can get from me for a character.