The Most Important Comic of the Past Five Years?

So, on Friday, I'm in my local comic shop and Tim, the owner of my LCS, asks me "What is the most important comic of the past five years?"

I had nothing.

Tim didn't either, nor did anyone else in the store. Nothing released in the past five years seemed to jump out as the most important book released.

I've been thinking since then and I've still got nothing. Nothing seems that important, that world-changing, like I'll still remember the first time I read it years from now.

Can anyone think of that comic?