With much deference to Albert's choice, I'll go with Herman Hupfeld's ageless standard from Casablanca "As Time Goes By", and give honorable mention to Al Green's "Let's Stay Together". As with "In My Life" though, neither of these are actually just straightfoward love songs in the mold of say, Bernstein and Sondheim's "Maria" from West Side Story, or Stevie Wonder's "You Are The Sunshine of My Life", to pick a couple of songs out of the air, but are all the more powerful for the difficulties they acknowledge must be overcome. Of course the question's loaded to begin with, but I think the real point is that from the unabashed simplicity of Buddy Holly's "Peggy Sue", to that song's (and artist's) complexly modern (modernly complex? Nah - most modern love songs aren't complex compared to "ATGB") doppelganger "Alison" by Elvis Costello, a great love song always remains a great song, period.
