Of the names mentioned, Hodgson is a good candicate. He has done wonders with Fulham, they aren't pretty but he is very effective with a small budget and seems to get more out of under achieving players. But he has said a few times he is happy at Fulham, he has little troubles there with no interference from above etc.
O'Neill is unhappy about not having finances at Aston Villa, despite often spending obscene amounts on average players. So other than the History of Liverpool I doubt there is much to tempt him, especially if Mascherano, Gerrard and Torres depart.
Kenny Dalglish would be the easiest option, isn't he already involved in some capacity with the club? He would appease the fans as he is a cult hero, but Newcstle tried that with Keegan and well he wasn't quite in tune with the modern game I think (although the board signing players behind his back wasn't right).
I think in the current state of Liverpool. Debts, fueding owners, top players considering their future and no big money to invest in new squad men....who would honestly risk it?