well, looking at the entry list my guess for this year is:
LMP1: Will be less interesting than last year. While "Henry the beard" Pescarolo could seriously compete with the over-weighted and air-intake-restricted Audi R8 in 2005, he'll be no match for the new R10 and the works team this year, he just doesn't have the resources, same goes for the other LMP1 teams. I guess we'll have to wait for 2007 to see a real battle in that class (Peugeot).
LMP2: I see no clear favourite and expect actually the same reliability drama as last year, when the best of the survivors in this class finished even way beyond the quickest GT2 car.
LMGT1: This is the battle to watch for! I see no favourite and expect a thrilling duell between the Corvettes and the Astons, but even a surprise Ferrari win is possible
LMGT2: Similar exiting as GT1 although I beleave that you still need a Porsche to win this class, the question is, which one of the Porsches will do it. But hopefully I'm wrong and the e.g. the Spykers will give them a chase.