I don't dislike any of the companions. They each have been given some distinct personalities, which is the low bar I have for these things. I think a lot of the hatred around them seems to stem from either two things; everyone is very special, they all have very dramatic backstories with histories that kind of clash with how they're introduced; they resemble so many overwrought D&D characters first timers make. Or people just don't like the character, and conflate that with them being a badly made character, Astarion is a flamboyant narcissist with some tropey affectations ergo he must be a bad character. On that note, I have to say Astarion's primary directive seems to be survival at all costs, so I wouldn't count on him being very loyal without a lot of work on the MC's part.
