Eh. Shouldn't your criteria scale for double albums? I mean, you're saying an album with 30 tracks is classic even if 20 are trash and 10 are dope/replayable. That means two thirds of the album is bad yet you're not only calling it a good album, you're calling it classic? What sense does that make on any level?
Overall the replayability argument is interesting though. I'll add it to my list of criteria for a classic. But I see it moreso as a sliding scaling. Some albums might have more of one criteria than another, but the total end tally must reach a certain level for me to consider it classic.
-Quality of music (nearly perfect to perfect tracklist)
There has to be a differentiation between an album that is good or great, and an album that is classic. One of the biggest problems today is that a really good album comes out and people automatically want to hail it a classic. That shouldn't be how this works. If you're album has a few middling or downright bad tracks, it's probably not classic.
-Impact on hip hop or music in general
Classic jazz albums are largely based around this. How did your album influence the genre, or music? This doesn't have to involve sales or success btw. Illmatic didn't sell well initially but it's impact is undeniable. Likewise there are underground albums that spawned entire subgenres or movements without selling much, such as Operation Doomsday.
-Replayability/standing test of time
Did your album simply spur a fad, or does it still have long lasting impact? Can I play it 5, 10, 15, 20 years after release?
-Critical acclaim
Perhaps on the lower side of my scale but still noteworthy to mention. How was your album received? Was it instantly hailed amazing/classic, or did it receive mixed reviews initially but slowly garner more attention as time passed and the trend of music became clear? Think about movies for a second. When It's A Wonderful Life came out it was trashed by many critics, it bombed in the theater, some people called it pro-communism or socialism. Yet for the last few decades it's been considered an undeniable classic film. Times change, as does our perspective and appreciation of art.
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You can scale things how you want but I feel like this is one of the most fair ways to do it, and helps include albums you might not like that had impact on the genre. I wasn't a fan of 808s And Heartbreaks but it's influence on modern urban music is dominant. Likewise there are Three Six Mafia albums I might call meh or ok that had dominant influence over how rap music sounds today.