Given the nature of the campaign, having everyone be a face, at least to some extent, seems like a top notch idea.
Now, onto the roles:
1. Strength Melee - DPS and Tank. Primary buff target for the casters, going to be doing a fuckton of damage, if they have the necessary support.
Strongest Candidates: Orion, Jericho, Alexander, Matheo, Marche, and many others.
2. Dex Melee - Off-Tank and Respectable DPS. Should be almost entirely self-sufficient, and bringing some form of out of combat utility.
Strongest Candidates: Ichabod, Derrin, Spidget
3. Ranged - Pure DPS. This is the party's big gun, the one outputting buckets of damage, and blowing up the big scary thing.
Strongest Candidates: Niccolo (though his reliance on 2hu's SoM alchemy nuker may knock him out), Ceraphine, Itsuko, Giancarlo (tho he could be either of the above too), Rae
4. Offensive Caster - Battlefield Control and debuffs. Your witches, wizards, shamans, etc. Not necessary, depending on the type of game the GM is running, can easily be replaced with another Support.
Strongest Candidates: Mouse, CCC, Eleanor, Kaerogi
5. Defensive Caster - Healing, Buffing, CC Scrubbing. These are the people who keep the party alive, and give them the tools to wreck face. The backbone of the party, and not to be under appreciated.
Strongest Candidates: Witch, Rintaelle, Sibyl, Illaria.
6. Flex pick - Given how the competition is shaking out, it's likely to be another Strength Melee, or Support Caster.
Given these roles, here's my party breakdown:
Strength Melee - Alexander
Dexterity Melee - Derrin
Ranged - Ceraphine
Offensive Caster - None.
Support Caster 1 - Sibyl or Rintaelle
Support Caster 2 - Illaria
Flex Pick - Either Witch, Jericho, Orion, or Ichabod.
Mental Stats: Charisma 3, Intelligence 2, Wis 1 (fitting for this type of story)