Hmm, I vaguely remember 'With Or Without You' and 'Still Haven't Found...' when they were brand-new radio hits (hard to imagine now), but U2 was still a bit off my radar when I was 11 years old. I do remember when 'Desire' came out, but I still was not really a U2 fan yet. So, I'll start with 'The Fly', which I remember extremely well -- in fact, I remember my best friend and I watching the first showing of the video on TV...
These are not the order in which I like the songs, but rather the order in which the singles were most successful in. . . er, blatantly commercializing an upcoming album:
1. Vertigo -- Immediate, hard, and catchy. Great video, and the iPod thing (although I have in fact never seen it) seemed to reach a lot of people. Even people who hate U2 would be forced to groove along with this uptempo winner. It built expectations to a fever-pitch and the album landed in at #1 everywhere.
2. Beautiful Day -- I hadn't listened to U2 for five years when this song came out (I didn't even know -- or care -- that they had a new album coming out). I remember exercising in a gym when it came on the radio . . . and I thought it was utter crap. To my amazement, it became a worldwide smash and introduced the band to a whole new generation. (Only after the album was critically-acclaimed and was a hit did I go out and buy it, and even then it took me a while to get into "Beautiful Day", but when I did get it, I really got it.) I now think "Beautiful Day" is a work of genius, and obviously it ate pop radio alive, but I'm still stunned by its success because it sounds pretty second-rate on the radio. You can't hear bass & drums on the radio, and those are two of the three things that make this song excellent (the other being the lyrics, and most people aren't paying attention to that either on radio). Go figure!
3. The Fly -- From the fans' perspective, this is maybe the greatest lead-off single ever, because it totally changed people's expectations and perception of U2, and in a very good way. In one 4-minute stroke, it cut U2 off from the hoards of bands who had died along with the 80s (Simple Minds, Tears For Fears, INXS, etc.), and put them at the forefront of the emerging 90s scene of alternative rock, demonstrating that they were survivors and that they were still very relevant (I admit I had my doubts before the album came out). But it wasn't a huge hit in most territories, being a little too left-of-centre for most American radio-listeners, so I can't rank it higher than this. . .
4. Numb -- I seem to rate this one higher than many of you; again, it's probably because of "my generation". To the alternative kids of the early-mid 90s, this was U2's coolest song ever, showing them to be edgy (no pun intended) and in sych with the times, not caring overly for big, slick radio songs, which was all good. The video for this song is a total classic. Edge was such an icon at the time that i remember being at a Halloween party at some college in 1993 (I was 17), and my best friend was mistaken for Edge even though he wasn't wearing a costume. . .
5. Discotheque -- This one failed to galvanize the masses. It's a tremendous song in many ways, but as with all the songs on the LP its production/arrangement had some issues, and it could have sounded a lot better if they hadn't spent 2 years mixing it. In retrospect, I do think the 2002 remix (on the Best Of) is way superior to the original (to some of you that's blasphemy, but there you go). The unforgiveable thing about this track is the video, which immediately ruined the song for me for about the next 5 years.
(Too early to tell for 'Get On Your Boots'. I'm just listening to it now for the first time, and it's not exactly blowing me away, but I assume it will be a grower. . . They're such a venerable corporation at this point, though, that they don't even need a big single.)
. It truly rocks!! 
