Hum, I guess it is a matter of taste... since we don't share exactly the same
I feel that some songs could never be as good live than on the album. Examples: MFN (although Montserrat version with Eric Clapton is quite nice, but any attempt at the intro live was close to a disaster - the worse being Sting's horrible voice in Live Aid), YLT (the intro was never rendered properly live), LOG (the 1983 version skips the intro and is just disappointing), WII (never had the same level of energy live), STP (James Taloy's voice on the album cannot be matched by MK doing both characters).
Some songs, however, have been transfigured by the live experience. Most notably: SOS of course, OUATITW, TOL, R&J, SR, MTS (Wembley'85 is so powerful), RATR (same comment), SAN of course (I have troubles to listen to the studio version now...), Marbletown, HFB, WAM (2002 live is awsome with sax), BLT
For some songs, I just can't decide. BIA for instance, the studio version is so sweet, despite what Mark says, it is not always better live. But the powerful rock Wembley 85 or Mandela versions are wonderful too; TR, we got some awsome live versions ('83, '96, '05), but the studio version is a masterpiece. Rudiger, good studio and live versions. Going Home, same...