++ [ originally posted by mikhail ] ++
IMO, all fingers point to Saha. Smith is the most like van Nistelrooy in playing style, but he's complimentary enough to play with him effectively, and he's the type of player Ferguson loves. He's also had an excellent start to the season. Rooney is possibly the most suitable style-wise to partner van Nistelrooy, and that partnership will probably be given a run to prove itself when they're both fit. Rooney'll do well.
Saha is clearly fourth choice in my books. He's perhaps not a whole lot worse than Smith (some argue he's better) but Smith has the attitude Ferguson loves so much. The question is whether or not he'll be okay with so much time on the bench.
That said, Man U at their peak had Cole, Yorke, Sheringham and Solskjaer, and Ferguson managed to keep them all happy.