A lot of people seem to like Zahua's quest and I have to agree. I think of the visions during the quest as symbolism used appropriately. Not insultingly blatant yet not incomprehensible nonsense. Zahua himself is an engaging character with a unique perspective (even if the stoner shtick is a bit overdone - thankfully, not to a point where it overshadows the other aspects of his personality). His voice actor also did very well.
The only one companion quest I didn't especially care for was Maneha's which felt a bit rushed and lackluster. She is a bit underwritten in general which is a shame because she has potential. In terms of the variety of the quests though I have no complaints. Self-reflection, coming to terms with one's past and trials of faith/ideals seem to be common themes. Which is a bit more nuanced than ("Everyone has parental issues". Yes, Mass Effect, I'm looking at you.)