Spray Foam has its Problems

It seals tightly and has some structural integrity, yet it can hide structural damage, and, if mixed improperly, vent formaldehydes. It is now effectively banned in the UK due to new insurance regulations. https://www.yahoo.com/news/lenders-reject-homes-spray-foam-000141562.html

Nothing better than fiberglass batts or loose fiberglass: they breathe and can be easily rearranged. And those crawlspaces should be encapsulated: no floor insulation required.