Opening Question

What is the best opening for black after white plays e4? Do you meet it with another King's Pawn Opening on your side, or is there a better way to keep white from advancing? I have to admit: I am predictable. I almost never use anything but Nf3, e4, and d4, and I am working on learning more solid openings. But I was playing the computer (level 4), and I came across that question. Is there a better way?

Here are the stats from the Explorer for their master game database.  C5 is most popular (the Sicilian) as it immediately unbalances the game.  It's not for the unprepared however.  The Dragon is kind of a rite of passage for a lot of intermediate players though as it usually leads to sharp play.