It always depends on who shows up, as last year proved. Did anyone expect Manning to suck so badly?
However if Seattle doesn't screw up like last week, I think they win, as except for receiving, they're a little stronger organically. The line is down to one point for the Pats, which indicates that the majority thinks it is a toss up. In fact, given the relative sizes of Boston & Seattle, there's an imbalance in the betting, which usually indicates that you should view the smaller city favourably.
That said, I want Brady to get his fourth, but I think Seattle is the new dynasty os we may see a passing of the torch.