Tossup I think between G1 Megatron and BW TM2 dragon Megatron. G1 because he's the original and still my favorite TF character overall. The dragon because he's my favorite Megs incarnation and probably my favorite TF toy. I still get giddy every time I see him rise from the lava in Blaster Master. Also rans would be Hot Rod, Rodimus Prime, and all the various Megatrons, Galvatrons, and Othertrons.