Aproximately dozen years back i started to notice that every second (mostly younger) roleplayer wish for his character to be "different" or "special" if you wish ... and i was so unlucky so i ended in party of pure vegetarian, teetotaler(?) Dwarfs, who never said harsh word, refuse to land a lethal blow to anything and all aspired for Magic ...
It was not pleasant experience. :-/
But it helped me appreciate Archetypical characters. :3
So i gues nobody can be surprised that my favourite is Lae'zel ...
I mean Niara done quite good job in her description and i can only say +1 to that, bcs in my eyes that is precisely Lae'zel ...
And that is also exactly why i love her. :3 Lae'zel is as Githyanki as much Githyanki can be and i believe its really good to have such character in our party.
About Astarion ...
I mean sure, he is narcistic and sadistic bastard, who see anyone except himself as puppets to play and is shocked when someone "obviously fail to see how happy they should be just bcs he allowed them to be in his presence" ... but once again, that is what i would expect from Vampire.
I dunno nothing about what Vampires are or are not capable to feel in DnD .... but it seems perfectly logical that when you live forewer (quite litteraly) petty throubles of meere mortals starts to fell ... well, boring.

It still pisses me off that we dont have any option to split his skull open once he dares to attack us, that indeed should be reverted ... i would not even mind if he only gets beating and have forcet cutscene where he surender. :-/
Second huge minus, not to companion itself, but to writing dialogues is about that he seems to be still "on horse" (not sure if english use this expresion) ... you often simply have no other choice but to forgive him, not bcs you want to ... but bcs Larian simply dont add other dialogue option.

About Gale ...
Now this one is a little problematic, i mean sure Gale is smug as Sephiroth ... but unlike the others i cant help the feeling that he earned that right.
That said IF he indeed was Archmage (i mean i would not be surprised if we find out that he was actualy not) ...
Personaly i dont buy all that crap about him being Good character, he is manipulative, he is secretive and he dont really care about others if he wants something (speaking about the Idol) ... sure, people could say that he needs it, or that his condition is forcing him ... but i cant help the feeling that this is only covenient excuse to hide his true nature.
I may be wrong ofcourse, but it just seems to me like true good character would try harder to find "another solution" than to jump over first one you find.
I believe he is more like Neutral ... and maybe a little chaotic too ... like yes, he dont wish to hurt anyone purposely ... but if anyone gets hurt, well he should have move sooner.
So in the end ... i like gale, oddly enough. Not as much as the other two, but i do ... his character seems interesting enough to me so i wish to know more.
Shadowheart ...
There could be whole books written about what is wrong with this woman ... or maybe more like girl.
I dont like her, like "at all" ... exactly for those reasons Niara listed abowe (+1 once again) ...
Since the way Shadowheart is written its like someone from Larian really hate us players and wish to tell us as often as possible and she is his messenger ... either that, or they simply tryed to create character with some duality (and failed horribly in my honest opinion) ...
There is nothing i would like at this character and it gets even worse as you continue playing and they keep push her litteraly under your nose. -_-
Honestly with every other alternation i like her even less, since as it seems to me, Larian is only adding another and another conversations and reactions for her, yet dont altern allready existing ... so we get to situation where Shadow is totally able to swear you loayality in first sentence and threaten you with death in next one. :-/
I said it countless times, but she seems to me like some Emo or Goth 14y old girl, who wish nothing more than being recognized as this edgy and "complicated" character ... who is dramaticaly pushing everyone away, just to keep herself in their presence ... but Gods forbid anyone who dares to ignore her! :-/
And Wyll? Ugh ... the only person i hate even more than Shadow. :-/
I believe that goblin who called him "Capitan Failure" described him perfectly ...
Wyll was a noble ... spoilet brat who had everything and never needed to work for that, so he didnt appreciated it ...
So his father send him to mercenaries ... but he didnt deserved that, so he didnt appreciated it ...
He could get some important life lessons ... concidering Flaming Fist captain, he never even bothered ...
Then something failed horribly, and lot of people lost their lives bcs of him ... so he signed pact with a fiend and get power ... and once again he never needed to work for it, so he didnt appreciated it ...
I dunno ... maybe i dont know the whole story here ... but Wyll seems like exactly that type of character who screwed something bad, then tryed really hard to make up for it ... but was too lazy to do that properly, and therefore we screwed that again ... and then again, and again, and again ... and will keep doing the same misstake over and over and over for rest of his life, simply bcs he never stops and say "damn ... i screwed that" ... no, it will allways be someone elses fault. :-/