Any main character from FF is fine imo. Cloud, squall,zidane.. even tidus!
Don't forget the old ones. Firion, Luneth, Cecil (MOTHA ****IN BAD***!), Bartz, anyone from FF6 (No real central protagonist, but probably Terra or Celes). Or if you wanted to go REALLY old school, Black Mage!
Guys..... Remember..... This is ALL-STARS. That's why RPGs are out
Joking aside, I do think that RPGs should have someone that represents them. What I don't like is people asking for characters of very underground franchises. It's all good, you know, those games could have been good, awesome even, and they could have give you hours upon hours of entertainment. But after the mist have passed, they're not games that EVERYBODY knows. Many people that I know that LOVE Persona and/or Disgea, are from the Otaku community. They go to anime conventions, do cosplay and stuff. And in that territory, those games are very popular. But outside that.... Not many people knows about them. Meanwhile, characters like Drake, Cole or Big Daddy are easily recognisable, there's hardly any videogame store without an InFAMOUS, Uncharted or Bioshock poster hanging around, or some special offer with those characters in it, and I think many casual gamers could not know their names, but you told them "It's the main character of XXXXX", and they'll go "Oh, yeah, that guy..."
I don't know, it's just my opinion. An opinion from a dude that doesn't like RPGs, but understands the importance of them in videogames.