This is always a fun question, I'm totally game for this.
Isaac (Golden Sun): Compassion IF he was one of the rare cases of a Compassion ring going to a GOOD example of compassion. The world's at stake and he still goes out of his way to help people, even if he doesn't need to or it would slow him down (Stops what he's doing to help Ivan and Mia, helps save Ivan's adopted family which is a totally unnessisary side plot, pulled a woman turned into a tree out of a river before she could drown...which makes more sense in context, even goes BACK to save a guy he doesn't even know from a rockslide).
But since Compassion going to actually compassionat people is rare, Willpower probably. Isaac watches his dad get crushed by a boulder and then gets nearly beaten to death himself a few minutes after that? He spends the next few years studying his powers to make sure he can protect himself and others. World is in danger of falling apart and his friends are kidnapped? He steps up to bat to go off in hot pursuit. A childhood friend seemingly betrays him and insists that the events Isaac's trying to stop need to happen? Isaac chases him across an entire ocean to get answers and to keep trying to save the world anyways. Dude gets a conga-line's worth of kicks to the crotch and still does his best to be a hero.
(Honestly, Willpower works for nearly all the original GS protagonists, they're all 'failures' that keep trying to be the good guys despite always coming up short or dropping the ball)
Tiki (Fire Emblem): Love seems very likely, the love the Divine Dragons have for humanity seems to be one of thier most defining traits, and Tiki is just as affectionate and protective of mankind as her peers. Plus her love for Robin (if the player chooses to get them to hook up) is really sweet and genuine despite the fact that Tiki knows she'll outlast him by thousands of years. Tiki seems to be a good canidate for both platonic and romantic love.
She could also be Hope, being the 'last of the divine dragons' and the oracle/voice of 'god', she's kinda a walking symbol of hope for the people who look up to and worship Naga. Plus her own dedication and belief in humanity and looking to the a better future seems like a very 'hopeful' way to think.
...Willpower probably works too, a lot of these traits seems to overlap a little in what makes you good for what color. Tiki's been alive three thousand years now, she keeps watching mortal people she cares about die, and have three(?) wars under her belt at this point and still gets up from her naps to protect humanity and try to save the world. She's kept her outlook pretty positive despite having almost every reason to give up or even go evil like some of the other dragons.
Lusamine (Pokemon): Love, a sick and twisted Love, but Love. Lusamine has done everything she has for her obsession and love for the Ultra Beasts, and despite her...craziness, she seems genuine in it to some extent (though she is being manipulated just a bit). And when she was healthier, the main trait we see out of her is being a genuinely loving mother and wife before the Ultra Beast Incident.
Could also be Greed, for how selfishly she desires the Ultra Beasts for herself, and how her obsession was more to benifit her rather than the Ultra Beasts too (at least, in HER mind it was for herself), but I lean more Love all things considered.
Might do some more of these sometime, these are fun thought experiments.
