He's a sneak.
And I gotta be honest, as a kid who was smack-dab in the target demographic in 1986?
Megatron bored the piss out of me. I've grown to like him more with time, but then? Boring black and white/grey (at least, that's how it read to me on TV and the printed page) robot mode, boring Alt-mode... the only thing of real note to me was his fusion cannon.
But Galvatron? Oh my god, I loved Galvatron! He's purple! That's the Decepticons' color! He should totally be leading them! He has an orange fusion cannon (not really fusion cannon, but w/e)! I love orange! He turns into a space gun AND a big cannon! He doesn't need anyone to fire him anymore! He actually killed Starscream! He's been cosmically-empowered by robot Satan and has this cool crown of three horns and a goatee now! He'll blast his own men if they piss him off! He has an awesome voice (Welker's; I didn't hear Nimoy's until a bit later).
Not everything holds up as much today, but a lot of it does, though like I said, I've come to appreciate Megatron a lot more over the years, too.
But for kid me? Galvatron was the hypest jive when it came to Decepticons.
Know what the tragic part is?
I never got to own a Galvatron toy until 2008.
Yes, that one.
I will add that, for a happy ending, today I am the proud owner of a Titan Master Galvatron, a Generations Select Galvatron, and a Legacy Galvatron (and I almost never double up on a mold).
Edited: Damn autocorrect. You WILL respect Frank Welker, dammit!