I’m honestly getting sick of Peter Cullen as Optimus at this point. It was cool when he came back for the first live-action movie because at the time it had been 20 years since he was last in the role. Now he’s pretty much the only one doing the role, and he’s not as good at it as he used to be frankly.
I think part of it is the material he has to work with. His Optimus in Transformers Devastation was awesome, partially because he acted a lot more like the Optimus I grew up with in the G1 cartoon. Tough, badass, but also willing to joke or taunt. Nowadays it just seems like his Optimus Primes are just dour.