Although Mercadian Masques is arguably my favorite set, and I have incredibly fond memories of drafting it, I voted for Invasion block. I remember drafting Invasion, Planeshift, and Apocalypse as being some of the most fun I've ever had drafting in general.
I have to agree with Soly's sentiment. Drafting three packs of Mercadian Masques sounds much more appealing than including Nemesis and Prophecy. Nothing against those sets, (sort of), but Mercadian Masques was just so rich and nostalgic. I'd get an absolute kick out of cracking three packs of Mercadian Masques one more time. Rishadan Airship beatdown!
I really hope it's possible that we can do at least one old school draft during the N.Y.S.E. Open weekend.
I'm looking at Sunday afternoon as the time for this; I figure that anyone who ends up in the Snapple bracket at the Depot Mox tournament can choose to drop and participate in this instead.