To the OP, youur missing an option, None!. Love them all as characters, that being said I certainly have my favourites, but that has a lot to do with limited spots.
Will probably take me 5-6 playthroughs to use them all actively.
The one I used the least in EA was Astarion closely followed by Wyll, but not because of their personality or anything like that, simply class/party composition. I did pop them out when I knew I would encounter stuff pertaining to their character/backstory though. And they didn't disappoint.
"They say he who smelt it dealt it." Sooo technically... this burnt corpse is your fault officer."
