I know people who worked in Big 4 and BP, in fact, lots of accountant in BP are from Big 4. You cannot say Big 4 is no better than BP, so why BP recruit Big 4er?
It really depends on what you want to do in future, if you want to be a CFO, finance controller, Big 4 is a must and fast way.
If you want to win from MBA, Big 4 is really not a big advantage.