At 3:31 the title cut of Joan Armatrading's 1977 album Show Some Emotion is easily under the four-minute requirement of a perfect pop tune. It also has a sweet melody and just enough emotional force. I'm surprised Armatrading's gem has not been covered often, because it seems like a great vehicle for a variety of possibilities. If you're among the few that are familiar with Armatrading's original, you should also check out Vicki Genfan's 2008 acoustic version.
In short I recommend "Show Some Emotion" to everybody's mix. Armatrading's voice, full of stance and nuance (Robert Christgau), should please most people, and the simple, bluesy production has aged well.