i think these stuff REALLY depends on what you plan on doing with the characters.
Snowe has great skill, he can take advantage of the level 3 Viper and Sword of Magic spells easily, and you can put a Kangacorn Rune on the third slot. characters that can use rides should when they start a fight so they can get around.
Millay has pretty good stats overall, but low HP to make up for it. she is pretty risky to use on a Kangacorn in Obel vs Skeleton Fists because they will critical her to death. I'd recommend a Counter Rune on her to help her survive.
i don't find great sword users good that useful at all. they can't get around and have poor skill. Coop has the most power but is slowest, Mitsuba has 2nd most power, is pretty fast, but can't get a 3rd spell in my game. Selma and Axel both get a 3rd spell (the Titan Rune 3rd atk is good) but only Axel has extra move but he's weaker and slower than Selma. Selma has Bulll's Eye to compliment her decent skill but you need to rely on the special attacks vs Skeletons than can Cross Counter and dodge a lot.
Eugene, but not for his spear, for his Firefly + PDF + EVA. he's extremely slow, though. Lino is slower though... terribly slow.
I think Ornela's very good with the spear because of her MAG, Sword of Magic and getting 3 rune slots. (Balance & Unicorn)
I'd go with Frederica for these reasons: ability to mount Owl (Seneca does not have), Extra Move (Flare does not have), Godspeed (Seneca does not have), and the only archer with the ability to equip Hand of God. Flare is the best choice for criticals, and the Yellow Merc has all those abilities listed except Hand of God--but he can use Ogre armor!
overall, i'd have to go with Mercenary Leader, actually. she has the highest SPD of all mages. however, she can't do Lightning Magic. then you need to turn to Maxine and Andarc. Andarc is a good tank (as well as Merc Leader and Katarina!). for highest magic after Wizard Rune and Extra Move, Simeon and Corselia fit the bill--but Simeon doesn't get the Jump ability (neither does Jeane)!! Corselia has superb evasion, one of the best in the game.
stat growth is random so if characters have the same growth potential, the final outcomes on who has higher stats will be random. also if you want actual power when doing magic spells, everyone should equip a Wizard Rune. then you need to consider both MAG and MDF to determine which mage has the highest magic. i have everyone with Wizard Runes, and with that rune, Jeane has the highest MAG. but she is slow and can't Extra Move and can't Jump.. lol
i find Akaghi and Champo extremely good claw users just because they are strong and can equip Hand of God. combined with the ever-useful Lion Rune (and maybe a Berserker Belt), they 1-hit kill 1-3 enemies (usually 1-2, 3 is extremely rare) while Mizuki can only target 1 enemy unless you give her a Lion Rune.. but she still can't deal the damage, only dodge a lot and counter. Counters are really weak in this game, they seem to not use Battle Lust and hit the opponent's front-side.
Wendel only has 80 in MAG in my game but that makes her a great candidate for Sword of Magic..
Nalleo, hands down. skill, power, speed, movement, power. this kid has insane growth in strength after level 30. better use a Balance Rune (or Master's Vest), as he'll be spamming his Gozz Rune attacks which all cause unbalance.
When it comes to axes Nalleo is better than Dario, but Dario has higher defense
they are about the same in defense in my game. Nalleo kicks Dario's butt