Many writings from the ancient world survive only because of quotes in other books. It's likely that works that were heavily quoted were among the best.

But of course, that doesn't preclude the fact that there may have been much better works that didn't make it to us.

Of course, I wouldn't doubt many excellent works died and will die in obscurity in drawers and caves.

Popularity seems almost arbitrary with elements of promotion (ads, influencers, celebrities, etc.), timeliness, and virality.