As promised, everyone's waiting in Mysidia. You can talk to anyone not currently in the party to swap them in. And while everyone's going to get a turn, and I have some sidequests I want to wrap up before I commit to following the poll... well, there's a poll. Vote whoever you want to take the first trip to the moon.
A party rundown:
Brent, formerly Cecil, can't leave the party. He's one of the tankier party members with his longswords and heavy armor, and can do a little support with his limited white magic. His Cover ability is mostly useless but will sometimes rescue someone who's at HP critical to keep me from having to revive them.
Lyrai, formerly Rydia, is all about direct-damage spells. Individual enemies get blasted by black magic, large groups blasted by summons. She'll be in the party for most of the sidequests, since most of the sidequests from here are to collect the last of her summon spells.
Friday, formerly Rosa, is an archer/white mage. She already has all the restorative spells available, from Curaja to Full-Life, and the full complement of white magic buffs. All that's left is Holy. She has a better damage output than MCE thanks to arrows being better at that kind of thing than staffs.
Disposable Ninja, formerly Edge, full name Edward Geraldine, no really, is a ninja. His physical attacks are terrible because his best weapons are swords, but he's too fragile to stand on the front row -- all his attack damage is halved. His magic is outshined by either of the two black mages. Really he's good at throwing! And that's about it.
Mars, formerly Kain, is a dragoon. Dragoons hit hard, and jump to hit harder.
Niku, formerly Cid, is an engineer. His ability to Scan enemies is damn near useless, but he makes up for it with some of the best raw strength and HP growth in the game.
Romo, formerly Edward, formerly Gilbert, is a bard. He can bark at enemies to cause status ailments and hide from danger, which is more useful than it sounds. He's even faster and more fragile than the ninja, which is kind of weird. His harps are long-range, so while his raw attack power isn't as high he doesn't get his damage output cut in half by being safe in the back row.
Kabbage, formerly Yang, is a monk. The power of his mustache lets him deal grievous damage with his bare hands and take hits that would fell lesser men. He misses his wife.
Zara, formerly Palom, is a black mage. Since he doesn't worry about summon magic, he gets the endgame black magic spells at slightly lower levels than Lyrai. He can Bluff his magic power up for the remainder of a fight. His Twincast ability with MCE still takes too long to be particularly useful.
MCE, formerly Porom, is a white mage. Since she doesn't worry about archery, she gets some of the endgame white magic spells at slightly lower levels than Friday. Her ability to Cry on command garners her the sympathy of lovelorn men on the Internet worldwide and allows her party to flee from battle -- but since Lyrai, Friday, Disposable Ninja, Zara, and MCE herself all get spells that also allow fleeing from battles, it's kind of useless at this point in the game. Her Twincast ability with Zara still takes too long to be particularly useful.