The impression I get is that Metatron is God's executive officer. Other than God's, there is no higher perspective of the Big Picture than Metatron's. Mystically speaking, "he" could be the first emanation out of the void in the action of creation.
If these angels were men, we'd be pitting physical strength and skill against broad vision and influence. Depends what you want to call more powerful.
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Shinier than a speeding bullet.
I think Metatron would be way higher. The reason is because, Metatron is said to have a "name like his master" because, I understand his name is numerically equivalent to YHWH? (I don't speak Hebrew, this is just what I've heard). True names are important in judeo-christian mysticism, so, on this basis Metatron has a "supreme" name. My understanding is that this is actually the reason he is so valued by Kabbalists.
Another reason why Metatron would win, is because there is a midrash where Egyptian wizards tried to ascend to heaven, and neither Michael or Gabriel could force them out; however, when Metatron appeared he easily was able to do so. Based on this I think Metatron is supreme in combat as well as authority.
On a biblical basis, Michael is a territorial angel, governing Israel, comparable to similar angels who rule over Greece or Persia. Since Israel is God's elect nation, he is first among such angels, but, compared to an angel like Metatron with a more fundamental role, Michael is more a "mundane" specimen.
Metatron is more of a behind the curtains enigmatic type of angel. Wasn't he human before? His name was enoch. How could a human turned archangel be superior to a pure archangel like Michael. metatron is more of a scribe. Like God's secretary.
Metatron is no archangel, I think he outclasses any angel... he is beyond any choir, he is a unique specimen. The highest choir, the seraphs, have 6 wings. Metatron has 36, which is 6 squared. I interpret this to mean, he is an "order of magnitude" above any other angel. With YHWH, all things are possible. I see no reason a saint like Enoch could not surpass an angel, if YHWH wills it. In fact, man is God's favorite creation; a fully realized saintly man, should have no fear of any angel. Plus, a lot of scholars don't think the Metatron who is Enoch is the same as the heavenly scribe Metatron.
Another reason why I say Metatron is higher, is because in the Kabbalah Metatron is aligned with the highest sephirot, the crown of the tree, this further attests to his supremacy.
The point here is Metratron is barely mentioned in the Talmud or the bible. Which are all canon. Metatron only exists in jewish mystic cults. Like the Kaballah. The book of enoch is non-canonical.
Michael has more feats in canon. While Metatron is an enigmatic figure who works behind closed doors. While Michael takes on a more active combat role in battles against evil. It seems that these two are at least equal but with different powers and roles. But most likely, Michael is the stronger of the two because of his many well known battle feats. He's more well established.
The only reason why he has "more feats" is because you just disregarded all of Metatron's... obviously, the Kaballah is "non-canonical" to those who don't use it... to Kabbalists, it IS canonical. If we include the bible only, Metatron doesn't even exist. Obviously, once you include an extra-canonical character, you've made the decision to also accept his scriptural domain of origin. You may as well say, Michael will lose because he has no feats if we go by the Bagavad Gita.
From my experience Metatron seemed like a shaft of light - almost like God if you will. Michael seemed, yes, like a warrior. I had known Michael and other archangels 1st & they seemed so immensely powerful to me. When I met Metatron I was shocked to notice that this one was even more powerful than the others who I had previously thought none were more powerful than.