it seems that shinji matou wins, this will be very interesting
If they choose they might as well end up with a marble reality show in the curious case that Shinji is as twisted as Shirou.
and that what he hates and likes is contradictory.
a little spoiler, he loves the rules, he loves to break them more, if they play his cards right they could end up with a marble reality related to that.
Read once that shinji's origin is predominance- the desire to be superior. A reality marble that enforces a kind of near equality in which he is automatically raised desinctly above his foe in terms of there greatest strength would be very interesting.
Oh no, I missed voting!
(Interesting choice. I don't know much about Fate/Stay Night but isn't Shinji...an evil jerk?)
He's an evil jerk in some, and an alright guy in like, one specific version that I've read, I don't keep up with the newer ones. In the original it's heavily implied that Shinji was deliberately developed and manipulated into being an antagonist for Sakura and desposable pawn by zouken. Like most fate characters he isn't locked into a specific end point that demands he become a villain.
Shirou for instance goes from a nobody kid who served as Kiritsugu emiya last good deed into haphazard spellcaster, into a badass spellcaster mercenary, into self loathing counter guardian who regrets his past sufficiently to highjack all of Rin's summoning attempts in an effort to kill his past self so his current self no longer exists.
Kalied prisma subverts this path for shirou entirely, somehow giving him a normal childhood and none magus upbringing, but somehow still having him become an orphan and get adopted by the emiya's.
Shinji starts as a rich brat with a chip on his shoulder, and degrades or rises from there based on his circumstances.
Matou's are pretty much an absent presence in Kalied prisma, and there is a lot of potential for recreating shinji from the ground up. There have been hints that shinji has the potential to become a heroic spirit same as shirou, and what really seperates them are there inspiration.