Who's the head honcho - Moses or Aharon?

Any society needs to have a number one man or woman. Someone who's the top. 

To the extent possible, you try to have checks and balances; usually, it's in the form of the judicial, executive and legislative branches, but sometimes, like in France, you'll have something called "bicephalous," literally two heads or two brains, where you'll have the Prime Minister and President coming from different parties, and when they're at odds, things can get messy. 

I personally had always thought that Moshe and Aharon, had in a way, represented different branches, or arms, each counterbalancing the other; at the "golden calf," Moshe chastises Aharon for being spineless; after Aharon's sons, Nadav and Avihu are killed in a heavenly flame, Aharon responds to Moshe's admonition that he should have eaten from the sin offering as insentient, and out of place given his personal mourning, and Moshe admits his error. 

Yet, besides the fact that Moshe needs to dress Aharon, annoint him, and bathe him - and ultimately undress him before Aharon dies, passing the mantle to his son, Elazar, in many respects Aharon is dependent on Moshe. In fact, interestingly enough, the Ramban writes that Moshe was the first Kohen, having consecrated the mishkan, presuming that Aharon never could have served if not for Moshe's initial service. 

That notwithstanding, the Torah goes out of the way to refer to Moshe Rabbeinu as "the man, Moses," and it would seem to be that this is the deeper message: for Judaism to be understood as genuine it needs to come from the man viewed closest to God (unlike Christianity which obfuscates between man and God), which means that Aharon's legitimacy, even his priestliness must come through the divine qualities of Moshe Rabbeinu, who nonetheless is referred to in the last portion of the Torah, V'zot Habracha, as not a man, but a "Man of God," ish ha'elokim, not detracting Aharon's legitimacy, but cementing it for eternity, and perpetuity.