Personally, I would just want an updated model, or even slight tweaks like arm proportions, ear curvature, and that damn back quill.
Though I do understand if people want a new model from the ground up, since some of the issues of the current model comes from the rigging.
Okay this is a discussion going around so I'm just gauging responses.
When you say you want Sonic to have a "new" model what exactly does that mean to you?