My favorite re-watch movie (or in this case, series) have been Neon genesis Evangelion.

I have mixed opinions about the show but rewatching it in different stage of life (early teen, depressed high schooler, stressed college kid, anxious junior to the worklife) I always saw some new things.

As a kid the robots and fighting the angels were the focus, as a depressed teen the religious symbolism and reading too much in to it was the focus, as a stressed college kid it was the relation between the characters (and their parents) was the focus, and finally as an "adult" it was seeing how completely dysfunctional every single adult is in the series.

A hallmark of good rewatchable show is to always explore new stuff. I wonder what I'll explore if I re-watch it in my next step of life