My list:
1. Optimus Prime: The most powerful, and most revered of Autobots. His quick disposal of Bonecrusher shown his power, and despite being owned by Megatron there is no equal.
2. Bumblebee: Probably has the most screen time of any TF, although I question his power over Barricade.
3. Iron Hide: His firepowers, that leap over that woman to dodge the missiles, and funny one-liners made him a stand-out.
4. Jazz: He's rather funny, but died a quick death and you don't feel bad for him because he has next to zero development.
5. Ratchet: Don't remember too much about him, except his line on Shia's hormone level.