Considering the quality of the content that I've seen in the last decade, I expect that your need for space will steeply decrease over time. What has been worth

Considering the quality of the content that I've seen in the last decade, I expect that your need for space will steeply decrease over time. What has been worth storing/saving the last 3-4 years? I mean really store, because you'll want to watch/play it again some day. The only things worth keeping are those hard to find with other means, some rare movies for example that are not available in any other form other than some avi found somewhere from an old vhs/dvd, but the rest...