Stone Sour do not suck. they're just different from Slipknot. i actually think Correy's voice is put to better use with Stone Sour, and Stone Sour have (drumroll) SOLOS which make them even better.
and of course there not as good live as Slipknot, but then again, there are only a few bands in the world who can compete with their live show (in my opinion)