Re: Spray foam vs fiberglass for rim joists to seal out air/moisture???
Howdy consider using acoustic caulk at the rim joist to the foundation it expands and contracts with temp changes and works great. The fiberglass does not restrict air flow- its first a filter secondly an insulator. Might add 2" of pink foam board into the ends of the joist bays and caulk or spray foam , use thee cans a little bead goes along way, The 4 by 8' sheets of foam board are easy to cut an install and a high R value per sw inch. Advantage is reducing the heat sink at the rim and the foam does not allow air movement.
Any an all of my comments are just my opinion and not to be confused with facts.