Uh, no.  Kefka has a lot more personality, which is pretty sad considering he's 16 bit... Sephiroth was a generic cookie cutter villain that has appeared in half the animes made in the last 30 years.  He was nothing special, his back story was completely retarded (Somehow just a few cells made him stronger than the people who had many many more!?? W.T.F).  Kefka actually had a personality.  I'll sacrifice a backstory anyday for someone who actually expresses some emotion and shows a real personality.  Character development >>>>>>>>>>> backstory.  You actually saw Kefka change and his goals and evil plots evolve as the story progressed.  Sephiroth started as an emotionless bastard, and ended as one.  That's all there was to him.  

Problems with Sephiroth: 

First of all, he's famous for killing Aeris, but he isn't even the one who does it.  WTF.  People love that scene but it wasn't even Sephiroth who killed her, it was freaking Jenova posing as Sephiroth.  Most of the time the "Sephiroth" you are chasing in the game (and throughout the first disc) is Jenova.  So why the hell do people love Sephiroth for something he didn't even DO?

Second, he barely even did anything.  He burned a village, oh no!  He tried to destroy the world with an asteroid, but failed like a whimp, while Kefka killed billions and reduced the world to ruins.  Yeah, Sephiroth was obviously more evil /sarcasm.  

Third, his story was reaking ridiculous.  It made no sense at all.  Somehow with only a very limited amount of Jenova's cells he was much stronger and able to comand others who had been more developed.  Thanks for the logic there Square!  Not to mention for most of the game he was nothing more than Jenova's puppet.  Hell, Sephiroth technically never left the Northern Crater for the entire freaking game (again, you were chasing Jenova thinking he was Sephiroth).  

Fourth, what's this crap about his looks being great?? He was a clone of Setzer from FFVI (even wore the same clothes).   And his freaking Sword had already been used in many Final Fantasy games, so he wasn't even the original owner of Masamune (It was much cooler on Frog and you know it!).  The name of that Sword is overused in Video Games as it is, but people act like Sephiroth at the original.

Sephiroth is a C Class villain at best.  The only reason he's so famous is because he was the villain in what was many people's first Final Fantasy game.  It's really sad because the action he's most famous for, he didn't even commit!  I would rank dozens of villains above Sephiroth, including almost every other FF villain.   

First you have the background completely off, you were NOT chasing jenova who looked like sephiroth, those were his many clones who WERE ON HIS COMMAND doing his bidding, so pretty much it was sephiroth all along.

Jenova was just bits and pieces he left behind then you would have to fight that piece

Never ever diss sephiroth, by far one of my most favorite villians ever, he killed one of the main people in FF7 and i dont see kefka doing that, its just pure evil and ill tell you right now made me feel alot worse then how kefka killed multiple people, but i never got emotional about it

First you have the background completely off, you were NOT chasing jenova who looked like sephiroth, those were his many clones who WERE ON HIS COMMAND doing his bidding, so pretty much it was sephiroth all along.

Jenova was just bits and pieces he left behind then you would have to fight that piece

Never ever diss sephiroth, by far one of my most favorite villians ever, he killed one of the main people in FF7 and i dont see kefka doing that, its just pure evil and ill tell you right now made me feel alot worse then how kefka killed multiple people, but i never got emotional about it

Yes you were.  You are very mistaken (I played FFVII too thanks) Sephiroth was Jenova's puppet throughout most of the game.  In fact, there is really no debate that it was Sephiroth who killed Aeris and not Jenova.  Jenova was the mastermind, and Sephiroth was rarely under his own control.  The Seph clones were pieces of Jenova under HER command, not Sephiroth's.  You were not chasing sephiroth, you were chasing Jenova.  People may have emotionally latched onto Sephiroth as the person you "Saw" killing Aeris, but Sephiroth DID NOT KILL HER.  I don't think you understood who was really behind most of the actions in that game.  Sephy did jack shit throughout FFVII, and spent the entire game in a damn crater.

Jenova was his mother? Well watever, sephiroth is extreemly power ful, especially in kingdomhearts. He is evil!!! Didint you se advent children? His mother didnt control shit. He was going to kill cloud but the stupid memory shit he did made him dissapear into clouds head. Sephiroth is ALIVE!!!!!!!!

Yes you were. You are very mistaken (I played FFVII too thanks) Sephiroth was Jenova's puppet throughout most of the game. In fact, there is really no debate that it was Sephiroth who killed Aeris and not Jenova. Jenova was the mastermind, and Sephiroth was rarely under his own control. The Seph clones were pieces of Jenova under HER command, not Sephiroth's. You were not chasing sephiroth, you were chasing Jenova. People may have emotionally latched onto Sephiroth as the person you "Saw" killing Aeris, but Sephiroth DID NOT KILL HER. I don't think you understood who was really behind most of the actions in that game. Sephy did jack shit throughout FFVII, and spent the entire game in a damn crater.

Edit: The clones were under Seph's command but Seph was under Jenova's.  That should clarify my position a bit more.   

yes i was wrong about that but sephiroth was still in command of jenova