I'd take any of Hiddink, Mourinho or Capello.
I wouldn't want O'Neill or Rijkaard.
Trappatoni and Lippi are quality managers but getting on a bit. Similarly I think Dalglish has been out of it too long now and would be a bad choice.
All hypothetical of course, the yanks won't sack Benitez because it will cost them. The only way a change of manager will come around is if Benitez walks. He's probably too stubborn for that though.