Honestly, all you need to know about Saerilith is in the Let's Play Archive. Reading that drivel without having to suffer for it is hysterical, especially given what the the player in that thread did with it.

How about the ones on the list?
Anything that can be cut out?

Link?

Here; think she first shows up in update 4. As for the others, I never dabbled with mods when I attempted BG2, so I can't speak to any of the others.

Out of that list the only one I've used is Kivan for BG2. Mostly because I never really understood why he wasn't in BG2 to begin with. The only reason I can think of is they didn't feel he was "interesting" enough. Always seemed like to me that with the resolution of his issue, Kivan had/has little else to do but travel with you.

I don't remember having any real issues with it. He was still Kivan, death incarnate. I always liked the idea of giving Kivan peace through your actions to be a cool idea.

I had follower mods back in the day (we're talking atleast pre-2008) but I don't know how many of them are maintained, or if they were well balanced realistically speaking.

I'd just grab ones that catch your fancy. That Illithid one interests me quite a bit.

I personally found Finch insufferable: annoying soundset and predictable, hyper-nerdy attitude. Plus she is a divine caster, and there are already enough of those in BG1, all of which are a lot more enjoyable to lisen to.

I also tried out Gavin for BG1, whom I ditched even more quickly than Finch. Preachy, holier-than-thou attitude and seemed like an uninteresting character in general.

For BG1, I liked the Mur'Neth (or however you spell his name) mod, but unfortunately he is not the most useful character around, as his class is pseudo-Thief with some unique abilities, and you can get much more versatile thieves from the vanilla cast. Still, the concept of his character is interesting, and his soundset is also well done and humorous.

I also tried out several NPC mods for BG2, out which I liked Ghareth who is a low-level Fighter/Mage with a straightforward and honest personality, and Keto who is probably my favourite NPC mod when it comes to writing, but unfortunately an unkitted bard is totally useless in BG2. Still, she adds a bit of quirkiness to the existing cast. Played a bit with Kelsey in my party too, but found his "guy next door" personality rather generic and boring, but from a gameplay perspective he can be interesting, since he is a Sorcerer.
Xan for BG2 I found so-so, his dialogues, while generally well-written, get old very fast since there are just way too many of them and - as you would expect from him - are rather whiny. Coran for BG2 way okayish, and the Branwen one was quite dull.

tl;dr, out of the ones I've tried I'd recommend Mur'Neth for BG1, and Ghareth, Keto and Xan (if you don't mind his constant moaning in his conversations with the PC) for BG2.