I think this is best version of MLK live is from the opening concert in Barcelona. Listen to the way bono sings it, very interesting and love how it almost has African quality to the singing. It too bad the song seems to have become more classic in its interpretation as the tour has progressed. As this version was far more interesting because bono was playing with his voice a bit. Love the "thunder - clouuuuuuuuuuuuuuuuuuud" part.
YouTube - MLK - U2 360 - Barcelona june 30, 2009
YouTube - MLK - U2 360 - Barcelona june 30, 2009