Let's start with a great discussion here on the forum? Who's more stronger? Sonic or Shadow? Don't just go around and say "SONIC!", give your reasons so the next poster could analyze your opinion whether he should agree with you or prove his point why it isn't.
So in my opinion, Shadow is more superior. Not because he's my favorite but he doesn't have killing restraints unlike Sonic who's still resisting the urge to kill or doesn't want to use his power.