Megs was a better warrior and tactician than Galvatron. But, Galvatron thanks to Unicron was considerably more powerful though this was clearly not proven when Rodimus only a few minutes to dispatch him into space. Megs battle with Prime was considerably more dramatic and displayed both leaders fighting prowess. I think Galvatron would’ve surpassed Megs in all aspects of leadership IF he remained sane, but that is just my two cents.

I just realised that Grimlock coulda beat any of those leaders in Rex mode. Series 1 and 2 Grim. season 3 Grim was so stupid he wouldn't remember who he was fighting. But with straight out raw power, he would and has.

Rodimus would be more powerful, and here's why:

 

Megatron and Optimus were equals, however, Galvatron was Megatron to the Nth degree, and Rodimus was able to mop the floor with Galvatron on a number of occasions. The only encounter Rodimus Prime had vs. Optimus was when Rodimus was affected by the hate plague and insane, and Optimus was coated in the metal that protected him, from the plague as well as increasing his endurance, therefore giving Optimus 2 advantages, sanity and protection. Keep in mind that Dark Awakening was Hot Rod vs. Optimus, and Hot Rod lost because he couldn't kill his idol, mentor, & father figure. Optimus was able to regain his sanity at the end with the help of the Matrix.

 

And also to keep in mind, in the Japanese continuity, Convoy recognized Rodimus as his successor/leader by giving him back the Matrix and sacrificing himself again. And also what was forgotten with the Rebirth series was at the end of the hate plague, Optimus gave the Matrix back to Hot Rod to refill. Now, adding on Powermaster Prime's strength additions, then PM Op would be more powerful than Rodimus, but regular Optimus was not more powerful than Rodimus. Also keep in mind Rodimus was never allowed to mature, so his true potential was never really shown, whereas Optimus was already the best he was gonna be.

They SAY Galvatron was Megatron to the Nth degree, but do not show it. And Rodimus may have been controlled by the Hate Plague, but he was still in control of his skills and Optimus still spanked him, knocking him out with ONE punch.

 

AND Rodimus had the Matrix, which is supposed to make him more powerful than Optimus since Optimus was without it, right? Well, we saw what happened. The real Prime took out the pretender.

 

Optimus giving Hot Rod/Rodimus back the Matrix in the Japanese toons (which most American fans haven't seen and could care less about) doesn't prove Rodimus to be stronger/more powerful. All it did was show Optimus sacrificing himself again to save the Autobots.