Oh man… That’s a very good question, which I actually haven’t thought about before. Hmm…
Hopper…kinda reminds me of Hitler, at least a little, or other leaders who’s oppressed entire groups of people. There’s something about the way he treats the ants which gives me such associations.
Hopper is also mean to the other grasshoppers, at least that’s what I recall - didn’t he bury some of them in corn from that dispenser?
And towards the end of the movie, when he beats Flik up - that scene really got to me as a kid. I think it was the first time I saw a character in a children’s movie take a beating of that sort, and it certainly made a strong impression on me.
Syndrome, umm… He wants to be a hero. Kinda. His intentions aren’t to hurt any bystanders, right? Sure, he kills superheroes (and don’t get me wrong, that’s horrible of course), but…his intentions are to save people..? (Though some people must have gotten hurt as his robot destroyed the city). Not to mention that he tried to kidnap Jack-Jack. That’s pretty darn evil too.
But overall, Syndrome wants people to look up to him. Sorta like Randall in MI, actually - he’s sick of being a nobody, and is willing to do whatever it takes to become number one.
He’s vile, sure, and he’s evil - but I must say, I think Hopper is worse.
And Waternoose… Urgh. Well… His intention is to save his company. After all, it has “been in the family for generations”, and of course he doesn’t want to be remembered as “the weak link”. Who’d want that?
What he does…isn’t good. At all. But at least he didn’t kill anyone? Sure, who knows what could have been if his plan had gone as planned and they’d actually gotten to kidnap lots of kids and use the scream extractor on them, but in the actual movie he didn’t kill anyone. Thankfully.
I personally see Waternoose as the main villain in MI, but I don’t think he’s as bad as the two villains in your ask, anon.
So to answer your question:
These three are all bad, vile and evil. But if I have to pick one, I’d go for Hopper, actually. Note that I haven’t seen ‘A Bug’s Life’ in a while, so I could change my mind, but for now, he’s my choice.
Waternoose and Syndrome’s stories seem to be starting out with good intentions that went horribly twisted and wrong.
From what I gathered in Waternoose’s story, he wasn’t just trying to save a dying company because it was in his family but because shutting it down would put so many of his employees out of work and there was already a scream shortage. If his company goes, the other scream providing companies won’t be able to keep up with demand and the monster world would slowly creep into a dark age.
As for Syndrome, his beef is that his dream was to be a hero, to be just like Mr. Incredible, but is betrayed when he believes that Mr. Incredible rejected him solely because he was a non super, that without powers he couldn’t be a hero, couldn’t be special. That misguided bitterness grows into an obsession to prove him and the rest of the supers wrong: Non supers are just as capable and with technology, no one will need supers anymore. Being a hero was a short term goal for him, a way to live out his childhood fantasy, but in the end he intended to make sure no one needed to call for a hero anymore, not when they can fix the problem themselves. In his twisted mind, he was getting back at the wrongs done against him and making it right.
Hopper, right from the get go, is a bully. He enjoys seeing others cower in fear, enjoys power and making people bend to his will, and absolutely has no scruples in killing people to make an example out of them. There is no benevolence, no misguided effort that drives him to do these things, only simply greed and scornful pride. Hopper does not even need the ants, the grasshopper are not unable to provide for themselves. He oppresses the ants because they were too dumb and too afraid of bigger monsters to say no and seeing them as easy prey, forced them under his heel with little care and no remorse. There is nothing redeeming about Hopper.
I think it says a lot that the evillest villain in Pixar history is a small greedy grasshopper.