I got bored with Aloth pretty quickly (can't even be bothered to commit his name to memory). I kinda liked his alter ego, and I'd probably have kept him if there was a way to make her take over permanently instead of dragging that weak-willed, mewling tree hugger along. But since that wasn't an option, and the wizard class didn't impress me, I kicked him to the curb when others came along.
Eder was a bro and has some funny banters ("If I'm not supposed to pet him, why is he so soft?!"). Plus, he makes for a crazy good tank. Any guy who takes that much punishment and doesn't whine about it (unless it's poison), is okay in my book.
Durance is crass as hell, but I loved him anyway. He's antipathetic by design, but he's got flavor and is probably the most memorable of all the companions.
Kana is just... meh. Kept him until the end because he summons ogres like a mad c***. Seriously, his ogre game insane. Other than that, he was largely just annoying with his happy-go-lucky bookworm attitude.
Sagani is mostly useless as a character. She's also the biggest basic bitch in the game even though she's an eskimo dwarf. Commoners on the street are more interesting. So is her pet.
Pallegina feels more like a teenager pretending to be a paladin than an adult entrusted with forging a trade agreement with another people. Sometimes I just wanna slap her, but hey, at least I care enough to do so.
Hiravias is the druid who dumps his Cha for that extra +2 to Wis. He's effective but pretty obnoxious. For me, he replaced Aloth as the primary caster and I didn't have any problem tolerating him, but I'm pretty good at tolerating anticharismatic characters who think they're funny.
I loved the idea of the connection with the Grieving Mother, but I would have liked it better if she wasn't a glorified midwife. I hate babies and I couldn't bring myself to care, so I left her at home after her quest.
So while the companions didn't overly impress me, I had to choose Kana as the one I liked least. I don't like his portrait, his story, his attitude, his voice, his hat, his family, his race; Pretty much none of it.
That said, for me, the biggest annoyance on the part of companions was the bloody companion quests that just wouldn't end (Durance, Sagani, Hiravias). I like to be able to finish side quests in a timely fashion, not drag them along for three bloody acts. Especially with characters that I don't want to take with me in the first place.