Holy crap, this is almost exactly the situation I was in!
Nope, I'm afraid! All the characters in that exchange are all protagonists on mainline FF's and spinoffs at the time of their EX being avalible.
Best two choices, in my opinion, are Y'shtola and Zack.
Y'shtola is very low maintenance, only requiring her EX, none of her other weapons are neccessary. She is a very good (very god) battery and delay soecialist, with emergency button healing and brave recovery from her massively Loaded EX+, with effects raging from being a free turn, raising people from the dead, recovering ability uses, being a slightly more powerful source of Max Brv generic buff for the party then another of her skills, making her immortal at above half health, the list goes on.
She's super amazing, and heavily reccomended!
If you DO have her, grab Soldier First Extraordanare, Zack Fair! He's not only an amazing and very survivable tank, but a massively powerful source of damage as well! He can place a special shield on himself that reduces and eventually negates enemy Brv damage, and does massive damage when targeted by attacks! He holds his own very well, and comes highly reccomended!
Anyone else is more of a gamble, and will require heavy investment for lesser payoff then these two. I reccomend above all...
...make sure you check your team and make sure you know what you need covered! Y'shtola is useful forever, but if you have plenty of supports, maybe a magic attacker like Terra could he help-Okay, I'm joking, Y'shtola is most important, no matter what. It'd be a waste of a token to get anyone else if you don't already have her.
