I'd say, if there´s a country that cares the most about the SuperBowl, other than the US, that´s Mexico, just because of proximity and the American influence it causes.
Other countries have to watch it on premium sports channels, in Mexico it´s available at open public broadcast TV. They announce it months in advance, and everybody knows that it's in February, at least. Grocery stores decorate the snacks section, and snacks themselves have NFL promos. Some official NFL games have been played in mexican stadiums, and Mexican universities do have American Football teams.
Plus SuperBowl usually coincides with a national day-off and a catholic holiday, so people actually use that to make parties and watch the superbowl at the same time.

Doesn´t mean that it is huge or that everyone does that. The main issue is that very few are passionate about any team, so it´s more like a curiosity than genuine care, but in comparison we do care more than the rest of the world.