Honestly, I don't have a very good opinion of Owlcat writing companions especially I have a problem with how good companions are written. There will be some spoilers, so open it at your own risk.
Seelah
The biggest problem I have with this character is that she shouldn't be a paladin. I hate it when the game doesn't follow its own rules. If that were the case, we would have to find a new paladin in act 1.
Camellia
Crazy serial killer. In itself, that wouldn't be a bad problem, but that's literally all there is to write about this character. Honestly, maybe it's a bit my fault because I was hoping for more mainly because the other evil characters are much more interesting. Let's ignore the fact that the whole secret of hiding alignment is very poorly hidden and it takes a whole 5 minutes of the game to figure it out (excluding the character cards). This is practically the Nok Nok from the previous game, except they removed everything that made this character funny.
Ember
It is not bad in itself. If she remained a half-mad prophet who wants to help everyone to the end, it would be good. The problem is how her history is written. As long as I was able to swallow the fact that in a moment she could convince the cultists to put his head under the ax. Later it got worse. It was to absurd how literally within 2 minutes of conversation she convinces a band of demons to stop acting like demons. It's just too much for me.
Arueshalae
A demon seeking redemption. Just why she had to be written in such a tearful way. She acts like a 14 year old for the entire game.
Wenduag
Probably one of the better-written stories in this game, the problem is that the very beginning is written in such a way that there is literally no reason to take her. Couldn't they really have written her introduction to give the player a reason to choose her over Lann? Random potential betrayal at the end of the game is also stupid and completely incompatible with the character. It makes no sense at all for her to betray someone who was able to kill the demon lords for the average demon at this point in the game. A bit like suicide with extra steps. It would make sense in act 3.
Greybor
It's hard to write anything except that it's a terribly boring character that might as well not be.
Nenio
Where to start. Of all the characters, this one has the least history. She literally has zero story to act 5 and worse, her entire story is tied to literally one of the worst dungeons I've encountered in the games. Even during her mission, she is barely present until you get to the last boss. The character was literally written as a joke just like Nok Nok (except he was funny at least). The worst part is that she's the only full-fledged mage in the game, but luckily there are mods.
In kingmaker, the characters were much better written. I have no major problems with other full-fledged companions.