hummm, this is certianly a tough call. i've heard bono say on many occasions that he can't stand mushy love songs, thus he's incapable of writing an upbeat love song from begining to end. i'd have to say it's a tie between;
so cruel: just read the lyrics. it's from achtung baby, which bono admitted that a lot of the lyrics were inspired by watching edge go through his divorce. the lyrics are extremely bitter. this is the song you dedicate to your ex. LOL
WOWY: the title alone is bitter. what worse of a feeling could there possibly be to believe that you can't live happily with someone, or happily without them? the lyrics are also very bitter and almost vengeful.
those are the two best IMO. it's ironic that WOWY is loved by so many women. i really doubt that those who consider it a love song have really listened to the lyrics. i always have a hard time explaining to them that there aren't really any good U2 songs to dedicate. most of them are true stories and tend to look on the darker side of relationships.
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"I hear Bill Clinton was out seeking foreign policy advice from the rock group U2. You may not know this, but they try to call me every night at the white house...when it comes down to it, I'll be meeting with Boris Yeltsin and John Major. Bill Clinton can stick with boy george." -George Bush Sr. (beware, THERE IS A JR.!)
"We're an Irish band. WE come from Dublin City, Ireland. Like every city, it has it's good and it has it's Bad. This is a song called Bad." -Bono, right before U2 took over Live Aid