What if Marvel and DC traded Villains for TWO years??

This has always been a dream of mine. Lets just say the  powers that be at Marvel and DC got smart and to shake things up a bit they traded villains for two years. What story lines would you like to see? How would you pair off the Villains/Heroes? Would you pay to read this crossover? How many of the books would you read if this was done in regular continuity?