Valuev. He faced some hard punchers and walked through their best shots. He was never down. Even one of the Klitschko's won't floor him (ok, because the fight will never happen - but that's another story).
I don't think Toney will ever be ko'd but he would take a sustained beating against either Klitschko which is why I'm hoping it never happens.
**** that. If James Toney fights one of the Klits, that dude is not making it the full 12. But if his fat ass was actually in shape and didn't have to fight 240lb men, then no, nobody is knocking him out.