Well, rather the point with Megatron is that he didn't
start off the worst of the worst and post-DOOP seemed to imply he was under delusions that what he was doing was for the greater good. His faction betrayal was largely due in part to finally realising that the Decepticons really, really weren't the good guys anymore. We don't really have any hints of any sort of conflict like that in Rodimus or Magnus and it'd be very out of left field; someone like Flame or one of the Monsterbots, sure, but the both of them would laugh off the suggestion.
Well, Rodimus would. Magnus would probably arrest you.
Optimus is... in a strange place right now. Technically he does actually have leadership over a small faction of Decepticons who want peace through Soundwave, though that's a bit complicated at the moment and it's been shown that even the cassettes aren't very fond of Soundwave's decision. Really hope that's something that'll be explored in future issues.
One possibility I didn't mention before actually is Sixshot, who was last shown to be alive in some capacity. A phase-sixer could easily intimidate desperate 'cons into following him - Overlord certainly had no problem on Garrus-9 - and it'd be a cool way to get the best furman-era IDW character into the book