I don't know who this Ghirahim guy is, and I'm trying to avoid Skyward Sword spoilers. So I'll ignore him for now.
My vote goes to Ganon, hands down.
I WOULD have said Zant was the most effective villain, story-wise, appearance-wise, intimidation-wise, etc. At first, he gave off that aura of total ruthless control, from the way he storms Hyrule Castle like it's child's play and the way he just gives Zelda her chilling ultimatum: surrender or die. He came off as incredibly confident in his power, and with good reason. That cutscene where he confronts Link and Midna in Lanayru's Spring is proof of what Zant could do; knock Link aside like a doll and manipulate Midna like a puppet, plus the chilling and merciless way he spoke.
That being said, after Ganondorf was introduced to the plot, Zant was kind of ruined, his role as villain tossed aside as a pawn and his impressive character torn down as a deranged madman. Really made me lose all respect for him.
This absolutely and totally sums up how I feel about Zant. It's quite sad, really. I wanted to love him as a villain. His change in mannerism later in the game
could have worked, in a Crazy Awesome kind of way, but the way it happened he ended up just being a doofus.
On the other hand, as much as it felt like it was done cheaply in terms of
storytelling, the fact that Zant did all that, and was the pathetic toady compared to Ganon, just gives Ganon that much more villain cred.
You can say the same about Aganimh, really: He had already pretty much successfully taken over Hyrule by the time the events of LttP got rolling. By the time Ganon became important, things had already gotten that much
harder.
But if
that's the metric, then Ganon wins even without being revealed as the man behing Zant's and Aganimh's curtains: He had taken over Hyrule all by himself in the original game. He had kidnapped Zelda and nearly taken her triforce for his own. There was not one single person other than Link who dared venture out into the light of day; everyone else was hiding out in a cave or a dungeon somewhere. That's probably the closest he'd ever been to total victory, with OoT coming in perhaps a close second (but he still didn't have Zelda until near the end). Of course that leads to another question:
That, is why i think he [Majora] is the most effective villian. That, and the timed "Game" he played with Link was one Link could not have won. Sure, majora was defeated in the end. But think of all of the timeline splits in Termina where link went back in time, and left the rest of the people to fall beneath the moon. Each time you go back in time, the world is crushed under the moon later in that time period. So no matter what, even if you saved one of these splits in the end. The rest suffered in spite of your heroism. Majora was the most effective villian. He didnt just make everyone suffer. He mafe them suffer everytime Link needed an extra three days to save just one of the worlds.
Okay, but that only holds true if the Zelda series holds to a multiple-universes view of time travel, which seems not to be the case since OoT is generally held to create at most two timelines, rather than a bunch of slightly varying ones, one for each time Link went back from the adult era to the child era.
Still, if you consider that Link's
only way of succeeding was utilizing time travel in a way he's
never had to do to defeat Ganon, it's still a good point in favor of Majora's effectiveness.
Indeed, the fact that at the very least, Majora got closer to victory than Ganon ever got is probably why he/she/it's such a popular choice here. But my question is, what kind of victory did Majora (almost) achieve? Basically all it wanted was to screw up as many people's lives as possible. It's easy just to go blow stuff up. Ganon's goals are much harder to achieve: He wants to rule, ergo there must be someone left alive to
be ruled, to cower in fear of him, to serve him, to beg him for mercy, or whatever he wants. So I guess it's a question of what it means to be effective, whether there's more to it than just doing a lot of damage.
Also I think Malo should be one of the poll options.