I'm still adamant that Wasteland 2 gave you some of the best "custom party" immersion, for lack of a better word. I really wish more games did what it did.
I've played so many cRPGs over the years, and have loved so many.
One that I always think back to was Wasteland 2. The story was fine enough, but what really drew me in was how the party worked. With your party almost assuredly being made up of characters you made, there was so much freedom to make stories for them.
I believe another user was actually discussing this exact thing recently, when ranking their favorite cRPGs and I wanted to double down on that.
The fact that there are different "dialogue traits" (even if it was pretty limited) that unlocked different avenues of discussion? It really helped lean into the feeling that the party was made up of different personalities that you crafted.
My favorite thing though, which I have never seen another cRPG do quite as well, is actually dialogue choices. Yeah, in every other game a party member might speak up after a dialogue trigger or whatever - but it's still scripted. Wasteland 2 letting you change the speaking character mid-conversation made talking to NPCs feel truly alive, like it was a group of people having a conversation.
Perhaps you had a typically reserved character/Ranger who only spoke up at certain times, or maybe you had another who tried to be the moral compass of the group. Or maybe you had two that were in conflict with each other's decisions, being shown by them offering up different opinions.
For me, this added so much to the game and it's why I bounced so hard off Wasteland 3. Seeing this feature get removed really took away my main interest in the game - and it's something I've desperately craved for another game to do but have never seen happen.