I only want good-oriented and honorable companions, and I need at least five of them because I will only be playing the game with a mod that increases party size to six. Someone already mentioned Eder. Yes I love Eder. In both PoE games Eder is my always-in-the-party companion. In PoE1 I also similarly loved Sagani and she was always in my party too.
I don't care at all about my companions being "nuanced" or "flawed" because that's what's "realistic." If I wanted any of that, I can get that from real life. I play my cRPGs to get away from real life.
I love Eder so much, he was a GREAT companion. But Sagani seemed dull as dirt, to me.
I only took Sagani for Eder's interaction with the fox. Otherwise she rode the bench, along with Kana, the boring paladin bird lady and Grieving Mother.
Durance was an amazing bastard and it was interesting to see him torn down and built up through certain choices. The Zahua (the drug monk) was another favorite in the expansion.