Friends of mine and I were talking about the idea of a canon or pantheon of great movies, and how to select them. We had a fun debate about the criteria, and eventually I drew up a list.
One must have concrete critical standards of some kind, or one ends up in a kind of death spiral of hopeless idealism.
Learning to find your own take on things you read or watch gives you a sense of what you can bring to your own work, too.