1) Niners. Obviously, a win over the Niners in the playoffs would be immensely satisfying, but the game itself, regardless of outcome, provides fodder for decades-long rivalries, the like of which we as Seahawks fans don't really get to enjoy that often. Seattle fans, in general, actually don't often get those kind of intense, timeless rivalries, and if we're going to start one with SF, there needs to be playoff games.
2) Bears/GB (tie). I'm sick of losing to both of these teams in the playoffs. I actually don't mind either team, and kind of pull for them in general, but I am SICK of the divisional-round exits against them.