Of those three, I might go with the Gibson simply because it might be the one that might be the most playable one for me.
I'm sure the Martin 5K would be playable, but I'd be too afraid of marring my investment playing with the amount of gusto I currently employ on a regular basis.
The Dias is an historic piece, but not necessarily going to be a player. And the Mehalona is going to be somewhere in between the latter two.
But you're also a dedicated collector. You're going to have all three eventually...