1. Movies I grew up with from pre~2000*
2. Movies I make a lot of references to.
3. Movies I'll always recommend people should watch.
4. Movies I'll always happily re-watch and/or re-watch frequently.
5. Movies which in aggregate could be interpreted as somewhat indicative of "who I am".
There's movies not listed here I've seen and liked which are widely considered to be classics along similar tastes, but they just didn't resonate as much with me so don't satisfy the criteria above. There's also notable exceptions because I've yet to see them, and they're on my todo list I feel guilty about not having seen yet, and regret not already having watched when I was growing up to solidify their place in my film vernacular.
*Movies post early 2000s I arbitrarily consider part of the "current"/"contemporary" age of movies. There's no hard date line, it's more about the vibe as some movies from 2000/2001 are in while others in the same year I consider "contemporary".