I think it's between Marcel and Trestman.
Marcel will get votes for great turnaround, excellent motivation, it's a feel-good story. Being a Canadian coach won't hurt him either.
Trestman will get votes because his team finished 15-3, had by far the most points scored, and by far the fewest points allowed. I seem to recall a lot of people last off-season (on this forum and in some press comments) suggesting that the Als were getting long in the tooth and were probably going to be on the decline in 2009, that maybe we could even contend for first place. Instead, they raised their performance to higher levels than ever and ran away with the season.
Both of these coaches made important contributions to the success of their teams.