Well, here's my case
Exhibit A: From Marvel Issue One
"But from Iacon, greatest of the city-states, there came a leader to inspire the Autobots in their hour of deadliest peril...Optimus Prime!"
"Of all the Autobots, only he, wise and powerful beyond understanding, was able to unite the scattered warriors into a fully effective fighting force."
This suggests that the Autobots were governed by a system of city-states, like ancient Greece...which implies that there would have been different leaders for each city state. I certainly concede that it uses the language of leader, but this sounds more like a classical "tyrant" -- which originally meant only a temporary military leader appointed during times of distress. (Later, tyrant took on the less flattering meaning that we think of today.)
Exhibit B: More to my point is this panel:http://i398.photobucket.com/albums/pp63/tresobyr/3D%20Models/opnotincharge_zps2c3d4bc2.png
The Autobots have a council of elders...one of whom appears to sit on a throne, and whom Optimus addresses as "Sire" (which can mean Lord, Father, or Elder...a "title of rank"). That panel does not seem to depict Optimus as the highest ranking Autobot, but rather as the highest ranking military leader.
Megatron calls no one "Sire."
Other versions of Transformers (and I'd concede later issues) depict Optimus differently, and I think the general impression is that Optimus is solely in charge.
I'm just making the case that looking at the original tech specs and the first Marvel comic, Optimus's authority over the Autobots could be reasonably construed as limited...certainly more limited than Megatron's.