I have all three, and they're very different drums with different vibes. It's hard to choose one over another, and as mentioned, the Legacies are designed to get the '60s sound, but it's done better. Classic Maple has more of a typical modern sound, perhaps a bit warmer due to the way the shells are formed (frequency instead of heat.) And the Keystones have a punchy, rock sound that speaks well. I'm using them on tour right now and am thrilled with them every time I play.
I dare say the Keystones would be a great choice if you had to pick one, and they're the least expensive. They don't come in a variety of sizes or finishes (yet) so that may be an issue if you don't like what they offer.
Bermuda