For coolest, its a tie of G1, Movie, and Animated for me. Lamest is obviously RID, but I think I'm in the minority when I say that BW/BM never did anything for me. Can't really comment on the Armada/Energon/Cybertron incarnation.

 

Best: Animated Megs

Worst: RiD Megs

 

Best by Personailty: Animated, BW
Best by Toy: Animated and RiD

Worst by Personality: A/E/C, RID
Worst by Toy: can't fill this in.

 

best is definetly g1 megatron, hes the most bad ass/powerful allthough movie megatron has potential of taking that spot

lamest would have to be rid

 

BEST: I would have to go with Beast Wars Megatron, followed by G1, and Animated

WORST: I would have to say Cybtertron, and Bayformers Megs.

 

Galvatron is the answer to both  

 

Best hands down no contest was Beast Wars Megatron. The whole iron fist in a velvet glove was just over the top cool. A nice touch to mix elements to make him intelligent and refined while also making him a brutal tyrant at the same time, yes. Really didn't hurt that he also got to play the part of the Devil so many times with Dinobot always tempting him instead of just using violence to get what he wanted.

Worst I've got to give to live action Megatron for not having a cool ranged weapon, and getting left on ice long just really made him a non-factor in the movie because it felt like too little too late by the end of the film. Okay and he gets defeated by a human, doesn't matter that Prime softened him up first he still got killed by a squishy.

Provided Megatron is not left on the ocean floor for most of the second film I think he could turn things around. If he actually becomes a factor in the second movie with his nice big arm cannon then RiD Megatron will take the lamest spot.

 

beast machines megatron. he was beastwars megatronm on roids in control of an entire planet

 

Movie Megatron had so much potential to be the best but what a disappointment. Great new voice IMO, really fantastic head design (with a little help from the fans), about 2 really cool lines, but let down with little screentime, no characterization and personality and mostly roaring, growling and rambling ALLSPARGZ.

Best Megatron is probably BW, for reasons already stated by others. Animated Megatron is close, but he needs to win seriously. I want the bad guys to win more often.

 

Coolest Megs: G1 (can't go wrong with old school), BW and Animated

Lamest Megs: RiD (he transforms into a hand, oooooookkkkaaaayyyy), Armada and Cybertron (they all get recolored into Galvatron... yeah, epic lame)