This is tough, G.I. Joe, Transformers and Ninja Turtles was the epitome for 80's cartoons. G.I. Joe was US Propaganda but I loved how the show always ended with a message.
"KNOWING HIS HALF THE BATTLE"
Anyways I'm torn, I love all 3 equally. Had toys and videos, cartoons and comics from all three. But If I had to choose, I gotta go with "G.I. Joe" cause of the variety of characters and designs. They were also the most flexable toys in the 80's. You could twist, turn, break, just about do anything with G.I. Joe action figures. Transfomers toys weren't as fun cause it always took forever to "Tranform" them. Turtles toys weren't as flexible as G.I. Joe. Also "G.I. Joe: The Movie" is Classic. Last but not least. Mikey, Ralph, Leo and Don. I love you guys for life. But I think Snake Eyes and Storm Shadow would give the turles that work: