I don't know that vintage speakers are the best or not but it might be true that more people will agree more often on models that have been around for awhile because more people have had actual exposure to these compared to any newly released model.
For example, I would be willing to bet that Klipschhorns, which have been around forever, would get lots of love from the masses compared say to some newer horn design that might be superior.
Generally, when something survives for along time, there is a good reason.
Kind of a form of natural selection, I suppose.