Most memorable NPCs outside of main scenario or sidequests?

[Tenkuu]

I do wonder if she recognizes 1.0 players, particularly those who made it through the story back then, or if she was afflicted with the same memory loss as so many others.

Minfilia remembers you if you are a 1.0 player, but none of the other Scions. This seems to point to Echo users as not being affected by whatever caused that memory wipe. If we think of it as being caused by Althyk, god of time and the one whose power Louisoix used to save the Warriors of Light at the Calamity, it makes sense that the Echo that can transcend the boundaries of time and space would offer a protection of sorts to its users against having their memories messed with.