Album- The entire Achtung Baby LP is, quite simply, a masterpiece. So on the question which of the two recorded LP tracks is better...no comment...
Live- The Fly instantly. You can listen to every single live bootleg with 'Until the End...' present in the setlist...then simply listen to the Live Version of 'The Fly' from Live in Boston 2001. The first time I heard this, I was absolutley amazed.
That version of that track is without a doubt the BEST version EVER. And completley beats the living daylights out of 'Until the End...'.
The guitar solo is absolutley astronomical. The amazing wailing sound Edge crashes into the song with at the beginning sounds excellent...and it just gets better and better...I am yet to hear a Guitar Solo courtesy of The Edge that beats it and was disgusted to see that U2 were too evil to blow the brains out of the crowd at their Slane Castle performance with another potentially outstanding performance of this track!
If they gave everything they got in terms of energy and attack at their Boston gig during The Fly, can you not imagine the atmosphere that song would have generated in front of a HOME crowd of 80,000 jumping fans?! Would have made 'Streets...' sound like 'Achy-Breaky Heart'....