I suppose I’m getting nitpicky here, but here it goes… in terms of what may have been the ‘best’ lead-off single, it may have very well been either The Miracle and EBW anyway. A large part of it is because you have some variation of the I–V–vi–IV progression present in both songs to an extent. It's used a lot in popular music, probably because it sounds nice when musicians are jamming or being creative and what not. Anyways, for The Miracle, it comes during the first and third part of the chorus riff and sort of gives it that ‘lift off’ feeling. Combine that with an aggressive guitar part and Larry’s use of the floor toms at the beginning, and you have something that's probably a bit more memorable with people more than other songs. Obviously, the song didn’t become their biggest hit in 20 years or anything, but it probably got someone’s attention during the iphone commercials and such that way.
EBW was the same way too. It used a more common version of that progression, except that it switched the first and second chords around. So take that and throw it with what is arguably one of Bono’s better lyric and melodies in years, and that’s probably why people look so highly towards the song. Again, it hasn’t exploded by any means, but I can't see many other songs on the album getting a similar chance to stick with some people.
Weirdly enough, I was looking up the chords to Volcano the other day, and its chorus supposedly uses an Em-C-G-D progression, which also falls into that particular progression I mentioned here. The people online couldn't quite agree on which order those chords were in, but that would be the band's third use of that popular progression on the album (and might explain why some people dislike the song for sounding too 'commericial' or whatever!). Maybe some of our guitar/music theory people on here can help clarify that a bit?