PaulB said:
You want one or more of the ingredients spirit, anger, soul, great lyrics, beat, feel, passion and surprise.
I'm inclined to agree with you. It's subjective though clearly, and I guess some are moved by technical ability as demonstrated in solos etc. Perhaps it appeals more to musicians (of which I am most definately not!) because they can appreciate the complexities.
My big brother was a fan of Led Zeppelin, Deep Purple, Genesis, ELP, Yes (to a lesser extent), Rik Wakeman, etc etc etc so I ended up acquiring quite a knowledge of it all. I could appreciate the musicianship of a great deal of it but it didn't 'move' me as such. I preferred my mother's Jim Reeves, Martie Robbins and Hank Williams' records for that! My personal tastes began to form (and I say this in all seriousness) with the release of Abba's 'Waterloo'! It's there that I discovered that I'm in love with pop music - for it's ability to speak to my soul, because it enlivens my being and I feel the joy of being alive. Cliches maybe but where I'm at!
To me, Mowtown (not that I'm a Mowtown geek) is the absolute zenith of pop music. There's something about it's very musical construction and invariabley yearning of the lyrics that just cries out to me. At the risk of serious derision, I can listen to something like 'The Shoop Shoop Song' and just be so happy to exist!

Though I would hastily like to add that I don't consider that particular tune to be (seriously) the purist Mowtown.