Neither, in fact. I'd prefer a scenario between those two, i.e. Seattle gets an early lead and comfortably holds it throughout, answering every SF score with a score of their own, on its way to a 14-ish point win.
The first scenario here usually involves the 49ers playing horribly or suffering in-game injuries (both happened last year), because with two pretty evenly matched teams it's very hard for blowouts to happen when both sides are playing their best.
The second scenario is just too much to sit through if you're invested with one of the teams (but great for a neutral fan).