See, I watch anything and everything, and I've only not seen 5 of those movies - The Endless Summer, The Bicycle Thief, Mar Adentro, The Best Years of Our Lives, Bridge on the River Kwai. And I've seen The African Queen, but I don't remember much.
A few of them, I've only watched once - and while I may not like them, I can see why others would - Eternity, Pride of Yanks, Waterfront, Mohicans, Braveheart, Field of Dreams, The Sting. I also don't like Unforgiven as much as others do.
Ben-Hur is overrated. It's pretty much the first major movie of it's scale which promoted it to greatness, that happened to carry over through the decades. It's overly long, and even moreso, boring. I don't even know why Gangs of NY is on here. It got mixed reactions when it dropped, and it mostly forgotten now. A River Runs Through It is another one that's boring. Other movies have done the "let's bond doing XYZ" better. I don't know why The Searchers is on here either. John Wayne's character isn't likeable at all, not even conflicted and compelling like they describe it...he's racist, and may play truest to his personality IRL. Chariots of Fire is another - the score carries the movie. Streetcar/Desire is ehhhhh. There's also no reason for The Untouchables to be on here. Hate Grapes of Wraith.
I don't think Remembering the Titans is must see, or Apollo 13. I don't like There Will Be Blood, or Das Boot. I like the remake of True Grit more than OG, but both are great. Western Front, I hate the book and the OG movie. Newman/Redford are like the OG buddy cop team with their chemistry.