Movies that endure tend to be more fun than things held up as best picture. Give me the Marx brothers over metropolis any day. Most of those movies suffer from that effect. There will be blood and no country for old men are great films but I can't think of a reason to go back to them. Desire to feel slightly anxious and sometimes be like "that's some good acting"? Million dollar baby and Slumdog millionaire aren't as good once you know the ending (for different reasons). Lotr obviously opens up the main stream to fantasy and will almost undoubtedly be the most recognized long term. It's giant in scale, has a huge franchise around it, has elements of fun, and if you skip the part at the end where everyone gets a monologue, the length isn't as punishing.