A big f-in T-rex. Screw trying to explain why. :D Seriously. I know a lot of fans want him to be a big ass tank like in the War Within comics, but I just say screw it and just make the dinobots transform into dinosaurs.
A giant animatronic T-Rex would be the coolest. Have there be some giant dinosaur animatronic statue that turns its head left and right, opens its jaws, and "roars" via a loudspeaker in its mouth at "Dino's Used Cars" or some shit. Make it rather dirty and rusty and chintzy, and then use the wear and tear and relative…