Is it worth comparing them? Some of the music U2 made in the 80's is absolute killer, the best of the decade. The first 2/3rds of the 1980-1990 Best Of is flawless in terms of individual songs. I don't think it's really worth dwelling on whether anything on their latest is "better" than U2 classics. The year is now 2004, and will shortly be 2005. By all means listen and praise U2 songs from 15-25 years ago, but I personally don't think it's worth measuring individual songs they produce now against ones they produced then.
Then again, I might be talking rubbish. To me, SYCMIOYO is a superb song, "U2 classic" or not. The very notion of deciding whether a song is a "classic" a few months after it's been out is pretty flawed anyway... was With or Without You a classic the second everyone heard it? I expect, like many songs on this album, it had to grow on people.