In the following order (imho, obviously):
Durance is the best companion, there's no debate possible there, even if you dislike him.
Next for me is Edér, he has a lot of dialogue and is also a fun companion and available right from the beginning.
Grieving Mother takes a bit to get to, but is written interestingly and has a lot of interaction.
Sagani, while not having the most interactions and greatest story is one of my personal favorites as well and has nice interaction with Edér. If I tried to be more objective, I would probably have to rate Aloth above Sagani.
Aloth has a pretty interesting story, but never appealed to me that much. In said setup a wizard would be pretty nice though and as I already mentioned he should be higher in my hierarchy :D
That would be a finished party already. Have to leave an honorable mention for Pallegina, though. If you don't make a tanky character, she would be a solid choice as well (I'd remove Sagani for her).
Hiravias and Kana Rua are on the weak side for me, although Hiravias has a couple fun lines throughout the game.
DLC wise I can't tell much, haven't had Zahua in the party (hate Monks) and neither the Devil of Caroc (too late in the game).
Maneha is fun, though and I'd rate her as high as Pallegina.