Lol so you didn't really like any of them ?
Well for quests, it had to be Lohse for the reasons above and other aspects that I dont want to give away because they are spoilers. She seemed to have a lot more impact on the game than anyone else except maybe Ifan due to stuff he did prior to the game. The problem with Ifan is his story is history game wise whereas Lohse was directly involved. Fane, was also heavily involved, but again it was historic. Sebille didnt really matter all that much. Her involvement was fairly removed from the plot overall though the elves themselves made an impact as a race.
I did not try the dwarf or the lizard yet though from what I saw, they both had some important some stuff happening in Arx but again, both seem somewhat disconnected from the plot based on what I gathered from pieces here and there without them in my party.