J. Lieberman, M. Bloomberg, and C. Rice would all be an epic disaster. It's hard to choose between the 3 as the worst. We are in serious trouble if any of the 3 become John McCain's running mate.
As for Colin Powell, there are many bright yellow flags associated with him. I certainly don't want him on the McCain ticket. Yet, of the 4 individuals mentioned, he's the only one who I can envision not being a major liability to the McCain ticket.