Well, if it's a vote you want:
[X] Tarot-themed Composite
Drawing inspiration from different sources is great, but it's frankly pointless to try to lock in on a preexisting design too strongly. Let's grab some good ideas from them all and patch them together. I've outlined my thoughts on the various systems below, followed by a detailed new suggestion.
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My thoughts:
The Servant Class Card System excels because it allows us to create role-specific buffs and such. Its weakness is that it leaves little room for considering the skills of the individual using the Card, and thus can become limiting...especially if some of our chosen have natural talents that are to broad to synergize well with any particular Class. Recall that this is an important issue in Fate: Servants, without a Class, are far more powerful than they are with one. Cu, for example, loses access to the bulk of his Rune Magic due to his Lancer Class.
The Pactio System excels at personalization. It builds directly off the Minister/Ministra's existing talents and personality, giving them a weapon ideal for them. It also offers telepathy, which is hugely valuable on the battlefield. On the downside, it isn't intended to be used by a group, and thus only doesn't offer much support for mutual support between Ministra. It also has a rather troublesome invocation ritual.
The proposed Tarot system strikes a better balance, allowing beneficiaries a far larger variety of Archetypes/Arcana to draw upon. It also fits the Solar mentality well, due to Tarot's narrative of continuous and unending growth.
...a Go based system makes little sense to me, considering the generic nature of the pieces, but I don't know much about the deeper aspects of the game.
Fairy Chess...I'm not knowledgeable about it. It sounds to similar to the Evil Pieces, but I can't say for certain.
Classic RPG based parallels the "game pieces" theme of the existing Pieces: Chess Pieces, Playing Cards, RPG Characters. Beyond the thematic, however, it's really nothing special. It does match up well with the Exalted Castes and Ability sets, but that's it.
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Tarot-Themed Composite System
So, what I'm thinking is that we use the Tarot Theme, drawing upon the Servant System for the core features of each Arcana, and add automatic personalization (based on the Pactio system)...
Each person would have a single Tarot Card of their own. That card analyzes their spiritual, physical, and mental traits and grants them access to whichever Arcana they are compatible with (potentially just 1, or possibly all that they are suited to). If they have access to more than one, they can switch between them by some means.
Aside from the powers of the Arcana, the Card also establishes a certain set of core benefits, unique to each user: An Artifact (only accessible while using the Card) based on their personal skills), and some form of permanent increase to the Ability and Attribute they are best with. Yang, for example, would likely receive a pair of Artifact Gauntlets, Dot(s) in Martial Arts, and either Dot(s) in Strength or Epic Strength. She would have access to these regardless of her current Arcana, and the Gauntlets would be usable regardless of Arcana (so, no matter what Arcana she's using, she's not going to get stuck with a sword or something).
I'd also recommend casual telepathy between all members of the team while the Card is active.
Obviously, details aren't all hammered out, and Alexander would have to help balance things, but...that's my suggestion.