I am looking for some fun old-school nonlinear RPGs (preferably NES and SNES)

[Rez09]

I don't know enough about MQ to speak to that one way or the other, but, if you decide to give it a try, just be aware of how extremely non-traditional the game is, both in terms of story and level progression. It doesn't use experience points like most RPGs, but instead characters gain stats randomly after battle based on the actions they took, and the story is told via many side quests rather than through a fixed narrative. It's a good system, albeit quite different, and if that sounds appealing to you, totally give the game a try.

I can also provide some quick tips to make life easier in the game if you'd like, as I've played through it fairly recently.