Renovation - Spray foam or Batt Insulation! Advice please!

I am way up north in Wisco, my last 2 houses were purchased new...1 with 2x4 construction and base R11 (built in 2006) and the most recent built 2 years ago with 2x6 and sprayed green foam...both full walk out ranches around 3000 sq ft. The difference in energy savings with the foam is remarkable.