They're all bad
I have a friend who won't buy gas at a BP station. I understand this, but I question whether BP is really worse than the rest of them. Have we forgotten the Exxon Valdez? How about the Atlantic Empress, carrying Mobil oil? The Amoco Cadiz? The Odyssey? Or is "forgotten" the right word for those last three? It's certainly not for the ongoing Conoco-Phillips undersea-drilling-leak currently (yes, right now) taking place in the Yellow Sea. (And that's what you're seeing in the picture, not the Gulf of Mexico.) You can't forget what you've never been told.
So I'm just not sure that selecting one company and not buying its oil is a rational response - unless you change out every time there's a disaster. If so, it's time to start shopping at BP again and boycott Conoco... After all, the Yellow Sea isn't isolated from the rest of the oceans.