My first set was a 1977 Ludwig. Since then I've had modern sets (that the ex made me get rid of) but I agree with this thread, the tone of my old Ludwig has never been matched by the Pearl, Yamaha or PDP sets.
But... I sent this weekend putting new heads on my 1971 Slingerland project and taking my time to tune then right. And I want to say that my vintage Slingerlands also have the "throaty warmth" that my Ludwig set had (and the modern sets don't.) And I know a local guy who deals in restoring vintage drums. He has Ludwig, Slingerland, Gretch, and they all sound good!
Maybe it's the thicker, three ply wood with mahogony, poplar and maple... maybe it's the hand sanding of the bearing edges... the single ply heads. Maybe it's the glue, or the way the wood has aged.
These old drums were made by hand, not by computer-aided presses, so maybe the small "flaws" in them give them a character (like the color and sparkle of a diamond comes from the impurities, not from the carbon.)
No matter what, I much prefer my Slingerland to anything made now. Of course I'll never gig with it. And should I ever get married again, well, the new wife has to understand that THIS set isn't leaving!