I didn't really gel with many of the PFKM companions. They were okay, but I wouldn't have chosen many of them as characters if I was setting a game up.
Amiri was one of Pathfinder's Iconics, and thus she started out as a stereotype before hitting PFKM. It was why you couldn't romance her, apparently. Paizo were uncomfortable with her potentially having a sexual element. As a companion I found her grating and boring; every stereotype Barbarian character rolled into one.
Jaethal was far too "oooh, I'm a special emo snowflake" for my tastes. The worst of being an elf and a voluntary undead. I rarely took her along because healing her was a pain in the arse and required the clerics to take feats to stop hurting her every time they cast group healing. Yes, she was a powerhouse in combat and had useful skills, but the downsides were too much for me to go down that route. I recall that the only times I really took her along was when I was playing a Necromancer or evil Cleric, and that was mainly for flavour.
Linzi... urgh. Another Imoen chirpy optimistic pain in the posterior. I rarely take to that sort of NPC in games.
So yes, writing NPC companions for CRPGs is tough. What some people like, others will hate. What some see as stereotyped and lazy, others see as iconic and defining. The answer to interesting companions in tabletop gaming is to write your own, but that doesn't work in a CRPG where they have established backstories and are important sources of plot.
