Those scenes still give me goosebumps, and I STILL get a little teary when Prime dies.
Megatron was the ultimate badass wasn't he? You think of all the cartoons from the 80's and the evil guys were always lead by cowards.
Cobra Commander from G.I Joe
Mum-Ra from thundercats
Tex Hex from Bravestarr
Miles Mayhem from Mask
Megatron didn't even back down against Unicron until he was about to be destroyed, and even then he kept trying to betray him.
I also think the guy who does the voice of Starscream/Cobra Commander has the best voice in animated history!