Much as I would prefer to see Obama win (mad though I think all flavours of mainstream US politician might be, it is important in symbolic value alone), I think that McCain is probably the marginal favourite at the moment (and despite the national share-of-the-vote polling) - largely because the Democrats are suffering somewhat from

a) high expectations of victory but
b) terrible insecurity after Bush II
c) a tendency to fight the last war (i.e. against Bush) rather than the current one.
d) a tendency to underestimate the effects of unvocalized racism in polling v. the polling booth
e) the mauling they gave themselves during the primaries, from which they will not fully recover

This race is extremely tight, and if they don't get their fingers out, the Dems are going to lose.