I'm not a model expert so I'd need an actual artist to explain why I feel like this but man I really do think the SfP models might be the best 765 models they've ever done
>Faces are much more capable of varying expressions than the StSn/MR model
>Eyes are shorter and softer
>Eyebrows appear above hair, harsher shadows, and outlines help make the model look moreso like it were a 2D drawing
>Head shape is slimmer, feels less chunky and potato-faced
>Nose shadows/shines make the face feel less flat, blush shadows look more natural
>Hair shape is much more exaggerated, tufts are much higher and twintails are longer
>Hair texture is more defined, likely using baked lighting whereas the StSn/MR model is just trying to let UE do everything
It's not a fair 1-to-1 comparison because the MR models are designed to seem like they could exist in a real space while SfP is very much a video game but my eyes definitely like looking at the right more.

I know Gakumas massively stole SfP's thunder but looking at screenshots of it make it almost feel like an in-between the two styles, not having nose shadows/shines and strict outlines like MR but also having slimmer faces, more expressions, and more baked hair textures like SfP. I know people use Gakumas as the king of iM@S right now but you still get some weird lumpy faces at certain angles in there so I'm not really sure if I prefer SfP or it but they're both pretty nice looking. They need to put Haruka in there so I can get another comparison