You retrospectively picked the winner (Facebook) of a bunch of companies in the same race. How would you have picked Facebook in 2007? e.g. MySpace vs. Lehman

You retrospectively picked the winner (Facebook) of a bunch of companies in the same race. How would you have picked Facebook in 2007? e.g. MySpace vs. Lehman Brothers Bebo vs. Lehman Brothers Friendster vs. Lehman Brothers etc