Has to be Bad for me as well, the song speaks to me more deeply than any other track in the entire canon, it has such a grip on me. I think in a live setting Streets is its nearest contender, but Bad still takes the title as the 'Ultimate Live Song' for me.
It's whisper to a scream structure is impeccably executed, there's a tension and drama to it, plus it has a real epic quality that no other song (such as Please, Kite and All I Want Is You) quite surpasses for me.
It's themes of adversity and turmoil work perfectly for the pay off at the end, when the band are in full flow and Bono unleashes those screams of pure defiance, 'I'm Wide Awake, I'm Wide Awake, you really do believe him. Whatever obstcacles were in his way he's overcome them by the end, he's been triumphant. I think of those screams as elation rather than desperation.
He's not really been able to rip into the song since 92, but it's spirit remains the same. Those eighties performances will always define the band and Bono for me.