MLK achieved tangible results.
Malcolm philosophized and waxed poetically but he was more of a boogie man than an actual threat to system. In fact, if Malcolm X constantly alluded to violence but never actually practiced it then doesn't that make him someone who talked all that noise in the relative safety of the North while MLK risked his life practicing what he preached down South?
MLK did not take us to the Promised Land, indeed he knew he would never live long enough to see it, but he at least laid the foundation. My biggest criticism of the Jesse Jacksons and Al Sharptons of today is that they are stuck in the 60's; they have yet to move beyond agitation.
In addition, I think instead of debating MLK vs. Malcolm X we ought to take a long look at W.E.B. Dubois vs. Booker T. Washington. That schism is far more relevant to our lives today.