The Gemara says of the three Melachim that visted Avraham Micha'el was the greatest of the three and stood in the middle, with Gavriel on his right making him the second in importance, and Refael on the left making him the least important. Based on what factors were Chazal establishing their order of greatness?
Eliezer Gersten, Israel
Micha'el is the guardian angel of Yisrael, which makes him the most important of the three.
Moreover, Micha'el is the angel of Chesed, and Gavri'el, the angel of Din (as his name suggests). Chesed -- on which the world was built -- is greater than Din. (It also explains why Micha'el is on the right and Gavriel on the left, as we say in Keri'as Shema Al ha'Mitah.) Refa'el, whom I assume is the Mal'ach of Rachamim, whose place is at the back (since he comes to heal a person after he has been stricken), is the least important of the three.
B'Virchas Kol Tuv,
Eliezer Chrysler