Ryan: This cover is incredibly well designed. The softness of Marian Churchland's art contrasts well against the rigidity of the main fonts. This is a fine example of how a great cover doesn't begin-and-end with just the artwork; a great cover is the culmination of the entire design--fonts, artwork, layout.
Kirk: This has to be the crowning achievement of these decade variants from Marvel. It's just a stunning piece that captures the 60's hippy vibe and even gels with the X-Men's current move to San Francisco. The amount of detail put into this cover is staggering as well, from the bubble fonts to backgrounds and even the colouring used. Wouldn't mind a poster of this one.
Runners-Up: The Unwritten #3, Green Lantern #43 Variant & Dark X-Men: The Beginning #1