My votes:
The lyrical messages in the first pair make an amusing contrast. "Imagine" is timeless, but the AC/DC tune is the one I've been covering in bands for the last 28 years. Dirty Deeds Done Dirt Cheap
Second pair looks like a heavyweight, but I find the Stones to be a surprisingly easy choice. Jumpin' Jack Flash
The Heart song never stops being exciting. By comparison, "Free Fallin" has five great intro chords, and then goes splat. Crazy On You
This is the song where McCartney figured out how to do a sappy ballad right. Let It Be