Although I included both in my earlier list, I do see alt-beginnings as different than an Alt-Clark story. In my own mind, I reference them as AU or Elsewords, but when I say Alt-Clark, I'm specifically referring to the character we met in "Tempus, Anyone."
A well-written alt-Clark story has a little extra umph for me because I came to know and care about Alt-Clark. He endured so much more heartache in his life (losing the Kents, his engagement to Lana, no secret identity, no Lois) than our Clark did, so it means that much more to me when Alt-Clark finds Alt-Lois.
I am curious now, C. What's in your top ten list? And when you referred to the one alt-beginning story, was that Jeff Brogden's "Lost and Found"?