I picked "Sunday Bloody Sunday." I really wish they retired that song at PopMart.
It stopped sounding like it meant anything after the eighties. When they played it during ZooTV, it was horribly out of place (the whole irony facade wasn't supposed to break down until "Running To Stand Still," so why do such an earnest song earlier in the set?; the Zooropa setlists that snubbed "Sunday" and "Bad" for the bitterly cynical "Dirty Day" work much better for me).
The PopMart reinvention was brilliant; they realized they couldn't play it with the same fiery anger as they used to, so they recast it as a lament rather than a protest. It was as poignant as it ever was, if not moreso. I'm glad they didn't keep playing it this way, since it would've cheapened those performances in a way, but they shouldn't keep playing it the old way either. The Elevation and Vertigo versions are simply going through the motions. It's just a pop song now; it doesn't mean anything anymore.
After that, I'd say "Elevation." It was a good tour opener, but I don't think it's strong enough to keep as a live staple, especially if it means "leaving behind" songs like "Stuck In A Moment...", "Walk On," and "Kite." I also don't think the modified intro works very well.
"Pride" sounds...tired. Maybe play "MLK" instead? I dunno.
"With or Without You" should never be played live again because Bono can't fucking sing it anymore.
I'm tired of "New Year's Day" and "Mysterious Ways," but at least they still sound good.
"Bad" and "Gloria" should make only intermittent appearances. They still sound good, and the band shouldn't ruin them by overplaying them.
"Where the Streets Have No Name" and "One" sound better now that they've tweaked them a bit. Are they better? No, not necessarily. But they're different, and good in a new way.
"Bullet the Blue Sky" is just slow and boring now. "Love and Peace or Else" should've replaced it, not supplemented it.
The Boy songs are awesome. They all sound surprisingly strong after all these years. I hope they keep playing them. "11 O'Clock Tick Tock" would rock too.