They are both icons in the contemporary Christian music world, however Michael W. Smith has been around a bit longer. He has written many genres of music-- contemporary, sacred, hymns, orchestral pieces, choral pieces and so on.
He wrote many of the songs Amy recorded before she began writing her own. They collaborated on many as well as when she became older and learned more. So he was sort of a mentor for her, as she came on the scene at the young age of 15 or 16. By the way -- Michael W. Smith wrote El Shaddai--Amy's recording made it well known.
So my pick would be Michael
** Note to : 'cheer142... on here:
You have obviously no knowledge of the history of these two artists, and no sense of Michael's talent as a songwriter and worship leader, and no sense of good music--- He is far from a loser-- he is a very talented songwriter/keyboardist/performer and has a great faith to share with all.