I think, but I could be wrong that Triple H vs. Edge is heavily rumoured to be a lock for the Main Event this Year at Wrestlemania, with Batista vs. Lashley on the Smackdown Side. So thats what we are likely to see, but here is what I personally would like to see.
RAW Main Event
Carlito vs. Triple H - This is a bit of a long shot, seen as Carlito would need to be getting his push and turn right now. However I think if they built Carlito up correctly, turned him heel, and have him win the Rumble, he could go into Wrestlemania with huge momentum, and he could come out with the Title. As a heel the guy has the potential to be huge for the WWE, and I think Triple H would be the best person to get this out of him.
Smackdown Main Event
Batista vs. Kennedy - I think only one of my two Main Events could logically happen, being that both of the young stars would have to win the Rumble in order to get over enough to warrant being in the Main Event, or Sub-Main Event of Wrestlemania. Kennedy is already hugely over, he would just need that Rumble win to push him over the edge in my opinion. To be honest I'd rather he worked with Triple H, but that is dependant on a roster switch between now and Mania.
ECW - I really havent watched it enough, or care enough to comment.