The Broncos are more popular than the Seahawks.
This map from 140 Proof shows which team each U.S. state is rooting for in the Super Bowl. It's based on positive social media mentions over the last few days.
Washington, Alaska, Kansas, Indiana, Ohio, and West Virginia went Seahawks. We have no clue why Indiana would like the Seahawks, especially since Peyton Manning played there and left on amicable terms.
Everyone else went Broncos.
140 Proof