Our custom is to say "Shalom Aleichem Malachei Hashareis Malachei Elyon Mi-melech Malchei Hamelachim Hakadosh Baruch Hu". So it is Hashem saying Shalom to the angels.
But aren't WE greeting the angels??
The Yaavetz felt strongly that this was a mistake and we SHOULD say "... Elyon, Melech Malchei". in other words, they are angels of "Elyon" - "On High" [i.e. Hashem] who is the King of Kings. But we are greeting them and not Hashem.
Rav Ovadiah Yosef followed that version and felt that we should too!
