To avoid undue influence I’m going to give my impressions before I read what everyone else has said, so apologies for any repetition!
As of the end of EA, I don’t trust any of the companions to put my PC or the group ahead of their own personal agendas. Which is fair enough, as we’ve not known each other for long, and while in some cases it might feel as though we’re tentatively feeling towards friendship, it’s too soon for it to be plausible that we’ve got there yet.
But some companions do seem to be more honest than others. My ranking, with the most honest first:
1. Gale straightforwardly tells us that there’s something he’s unwilling to share, rather than lying. He seems to value magic over people and in the past has taken huge risks with his own and others’ safety but it feels as though he’s learned a lesson and is trying to do better. And I believe, once he opens up, he’s honest about who he is and what his motivations are.
2. Astarion initially tries to hide he’s a vampire spawn, but that seems understandable. Once that “secret” is out, I believe that he shows us who he really is. Okay, that’s an apparently selfish individual who is going to prioritise his own safety and getting power, but I don’t think he lies about it.
3. Lae’zel seems to be a good githyanki soldier, but I’m not quite buying it. Her fanaticism and what feels almost like a personal obsession with Vlakith may be normal in her society, but I wouldn’t be surprised to find that she’d put noses out of joint back at her crèche and was in some sort of disgrace. I’m not getting a sense of any deeper dishonesty, but I do get the impression she’s putting on a front.
4. Wyll gives us the most reason to distrust him, given he asks us to kill the goblin leaders to save the tieflings, then when he has to admits he actually has an ulterior motive of a grudge against goblins, which still turns out not to be entirely honest as his ulterior motive is actually tracking down Mizora. Plus we don’t know what he’s already done at her behest or what finally led him to say no, it feels as though there’s still something to discover about what happened with the goblin raid that led to him agreeing to the pact in the first place, and he seems to have quite a temper and a lack of scruples when it comes to getting what he wants. I think we probably do know who he is by the end of EA, but given his history I’m not confident enough to trust him.
5. Shadowheart rings all sorts of warning bells for me, even more so now she’s been made “nicer”. It depends to some extent how you interact with her, but it feels to me as though she’s trying to worm herself into our good graces by means of flattery, selective honesty, and subtly driving a wedge between our PC and the rest of the party. I’m sure I wouldn’t be as suspicious if she weren’t a Shar worshipper, but given she is it’s hard not to notice that so much of what she says could be taken as manipulation. And it’s to her credit that I’m not 100% sure she’s not honest despite the fact I know she’s a trickery cleric serving a goddess of secrets, and in some playthroughs she’s the one who most genuinely feels as though she’s becoming a friend. I’ll actually be disappointed if it turns out she wasn’t putting on an act.
Now to read what everyone else thinks …
"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"