I think that Ignatieff will win.
I hope that Dion wins because he seems to be a man of integrity especially when Martin took over and kicked out most of Chretien's ministers (Copps, Manley, etc.) including Dion. Martin allied himself with the foot-in-the-mouth, Jean Lapierre. Dion didn't do or say anything negative and showed a lot of integrity and loyalty to a leader that didn't deserve it. Eventually because of pressure Martin was somewhat forced to name Dion as the environmental minister.
However, even though I hope that Dion wins, he is not bankable in his own home province (Quebec) where a lot of francophones think that he is a traitor (for being the father of the Clarity Act). He is also not bankable in the Western provinces. This means that if he wins the Liberal leadership, it is very unlikely that he will ever become prime minister.
In terms of opponents, I think that Harper and Duceppe will have the toughest time with Dion. The only negative thing that Duceppe can say about Dion is that he is a traitor for introducing the Clarity Act.
We all know what Harper will say about Rae (his mismanagement of Ontario while Rae was premier). With Ignatieff, Harper will say that Igantieff was out of the country for a long time and Ignatieff also has a habit of speaking before he thinks and then backtracking.
Whoever wins will be no match for Harper unless Harper creates a major blunder. Bigger name candidates should have tossed their hats into the liberal leadership race like the ex-premiere of New Brunswick.
I predict that Harper will unfortunately win the next federal election. Remember, you heard it from me first!