Here's the basic idea.

You take whatever idea of good and bad you have and try to scale it for the villains of the FF series.

1 characters are people who have done wrong things purposefully but perhasps for reasons you can understand or sympathize with.
10 is the embodiment of evil. They are wicked because...they jusst are. They kill without remorse or care and have absolutely no excuse or redemption for what they did.

For example, I'll list a couple characters froM FFXII since I just finished it.

Gabranth - 1. His emotional turmoil over the loss of his homeland made him very confused and unstable despite his cold demeanor. He also redeemed himself in the end by protecting the life of an innocent boy. Still, he killed innocent people and would have gladly had Ashe kill more.

Vayne - 6. His desire for peace is admirable but his would be a peace enforced with bloodshed. The ending showed he had no qualms about killing thousands of helpless people to serve as an example. He also killed his father and brothers so he might gain absolute power.

Feel free to list your own rankings for any Final Fantasy antagonist/villains.

It's important to remember these are your ideas of good and bad. My ranking might not fit with anyon else's because my ideas of right and wrong are my own.

Sephiroth - 1
Kefka / Zemus / X-Death / Garland / Shadow / The Darkening Cloud / Enuo / Garland / Vegnagun / Ultimecia / Adel - 10

Sephiroth is a 10 as well. He has no motivation other than he wants to be a god. Even if it kills everyone on the planet.

This is a nice concept I'll give it a try.

Seifer - 5 He wasn't exactly a bad guy, but he sure wasn't pullin any punches. The guy had some serious problems with his self esteem

Kefka - 10 I mean, honestly. Just die... Something of the sort.

Gabranth - 1 I agree with The Anti-Existence

Golbez - 4 He was a bad guy, but he still felt some kind of remorse, at the very least towards his brother.

Ultimecia - 10 A villian with absolutely no purpose, but still she was a killer. She wasn't really presented doing anything else in the game to be honest.

That's all I can think of right now.

Interesting.. I'll give this a go, in series order.

I - Garland gets a 10. He has no motives, he has no emotions. He enjoys wreaking havoc. End of story.

II - The Emperor of Palamecia gets a . . . 7. I always got the feeling he was really more so at the mercy at whatever higher power was giving him his demonic powers, sort of like [does not state character's name so as to keep it spoiler-less] is at Emperor's mercy.

III - Haven't played enough of this one to know anything about the villain. . . .

IV - Golbez gets a 1. He's no bad guy. Hell, he'd probably join the party if it weren't for Zemus' mind control. But, then there'd be no game, so . . .

V - Again, don't know enough about Exdeath as I haven't played this one all the way through yet, but so far I'd rank him a 6. This will change, I'm sure.

VI - Kefka? Shit, there's an 11 right there. No, make it 12. Play the game to find out. 'Nuff said.

VII - Sephiroth is . . . not really so much a villain as he is a misunderstood hero, so . . . I'd go with a 3 for him. Not entirely good, but certainly not fully bad, either.

VIII - Wait, who's supposed to be the true villain, here? If Edea is supposed to be Ultamecia's avatar into the world from her time compressed realm, then I'd give Ultamecia a 10. She's probably pissed because they don't offer manicures in time-compression.

IX - Ahh, my game. Kuja is a definite 8. He's no Kefka, but his origins, and taste for power make him a very diabolical soul to be sure. Not to mention he'd willingly destroy the crystal that gives the entire universe life. Now that's just plain cold.

X - Again, who can we really call the 'villain'? Sin is just a giant mobile armor, when you think about it. Yu Yevon is just a floating blob with legs and a really bad temper. Jecht is . . . a guy who was in the wrong place at the wrong time. But Seymour . . . whoo boy, there's a maniac if I ever saw one. I'm just gonna go ahead and do this: Jecht, 2. Seymour, 10. Yu Yevon, 5.

XI - Haven't played this one at all yet.

XII - I'm not nearly far enough into this one yet, and I'm doing my best not to read anything anyone posts that spoils any of the story.

XIII - Lol, of course I haven't played this one yet. I'd give those soldiers Lightning's fighting in this one video I saw a 10. They don't look too friendly, or like they'd be persuaded to sit down to a cup of coffee and talk things over.

Hmm, interesting idea. Let's see...

FFI: Garland/Chaos - probably a 5 or a 6. Sure, he throws himself into the 1000 year Time Loop, sets the Four Fiends to steal the future's prosperity, and becomes the avatar of Chaos, but it was stated that before all that he was actually a pretty nice guy. Apparently Dissidia reveals more of Garland's backstory (which wasn't mentioned in the original FFI), but I haven't gotten all the Chaos and Cosmos reports in it yet to uncover that. So it's a matter of conjecture.

FFII: Emperor Paramekia - definitely an 8. This vain, megalomaniac warlock sets his country to war, builds a giant air battleship, enslaves a town to build it, and then finally sells his soul to the devil for more power. Although Dawn of Souls shows that again he still has a good soul deep under all that darkness, I still think he's a pretty nasty type.

FFIII: The Cloud of Darkness - 10. She's a metaphysical embodiment of evil. Enough said.

FFIV: Golbez - 7 or 8. Yes again he does some pretty heinous things, but it was all revealed it was because of being mind-controlled by Zemus, especially as he was shown to deeply regret his actions, particularly towards his brother. This is particularly made clear in Shantotto's taunts towards him in Dissidia: "Armour does not hide hesitation!" :p

FFV: X-death - 10. He's evil sealed into a tree. Like Cloud of Darkness, his sole purpose is destroy. So yeah, he's completely unsympathetic and immoral. Which gives him a big 10.

FFVI: Kefka - 6. Why 6? Sure, he's probably the most insane, horrifying and thoroughly evil antagonist to appear in an FF title, and yes, he accomplishes his goals (as vague and self-destructing as they are), but that is only dealing with the present. It fails to remember the actual cause for his insanity - Cid's Magitek infusion, something which might have been carried out against his will. So, like Sephiroth, it seems Kefka might have turned out to be an alright guy, if he'd had the chance. But alas...

FFVII: Sephiroth - 6. Again, as the flashbacks in FFVII and also in Crisis Core showed, Sephiroth was actually a nice guy, if a little stoic and taciturn. Because of Hojo's insane ramblings which he misread and misinterpreted however, he snapped and got the whole 'god complex'. Causing him to become a four-time loser. So only a 6 from me.

FFVIII: Ultimecia - 7. Talk about a wooden antagonist. You see her for barely a minute at the end of the game, for her to ramble on in a bad German accent (which was changed for Dissidia curiously) about how she hates SeeD. Yawn. And this was supposed to be the big, bad evil sorceress from the future (and, as it turned out, the source of Edea's sorceress powers). But still, although the Time-Compressed World wasn't really a 'true' representation of the future, from what could be gathered her reign wasn't any utopia. Death, destruction and poverty seemed to be order of the day for her, in true megalomaniac style.

FFIX: Kuja - 8. Although he was trying to be a cross between Kefka and Sephiroth, his obsessive vanity kind of puts him over the edge. He might have set Alexandria down a path of destruction, but after his final insane act (attempting to destroy the Crystal of Life, as he thought the universe has no right existing if he couldn't either), on his deathbed, he recants his actions, realizing the futility of it all. Which makes his appearance in Dissida somewhat puzzling. But I digress.

FFX: Seymour - 4. I'm sorry, I just can't take this guy seriously. That ridiculous hairstyle, and his squeaky voice, make him more comical than imposing. But I have to admit, he does have determination - not even physical death stops him (I'm not even going to mention his attempted marriage to Yuna). But still, he eventually ends up folding like a deck of cards.

FFXI: Shadowlord - 4. Saddled with probably the most cliched name imaginable, FFXI's original villain proved ultimately to be probably also the most tragic in the series, being none other than Raogrimm, the lost galka 'talekeeper' (or elder), now corrupted into the Shadowlord's twisted form by the Zilart princes, by manipulating and amplifying his race's instinctive anger and grief over losing Cornelia, the only person who actually cared for him. He may have enslaved the Beastmen and launched the most destructive war in Vana'diel's history, but in the end, he redeems himself after his awakening, sacrificing himself in order for the player's character to escape (I won't spoil anything more).

FFXII: Vayne - 7. From the moment I first saw this guy, during the parade in Dalmasca, I thought, 'now that's the worst disguise I've ever seen, he's definitely the main villain.' And sure enough, it turns out he's exactly that. His Machiavellian scheming from behind the scenes as he attempts to usurp the throne of Archadia might be explained by being manipulated by Vernat. But that could just be a cop-out for excusing his own evil machinations for power.

FFXIII: ? I haven't played FFXIII yet so I have no idea who or what the main antagonist for this is.