I find the best moments of Optimus Prime (Primal) are when he's acting as the Dad to the Autobots. Like in Enter the Nightbird, when he tells off Wheeljack and Ratchet for mocking the robot. "We're here to guard the robot. Not make jokes at its expense." Primal has his own moments, particularly with Cheetor, Garry Chalk told me that with the relationships, Rattrap was like the bratty kid who he had to bring into line, Cheetor was the son who he had to drill some responsibility into. One of my favorite moments was in Prime in Speed Metal where after Knock Out is stopped, Optimus looks at the other bots and says "Explanations can come later. From all of you." in this disapproving dad tone that lets you know that the Autobots are in trouble.