Insulation and air barrier in a single pass - foam is the answer where air sealing and R-value have to happen in the same inch.
Closed-cell foam brings the highest R per inch, structural stiffening and a vapor barrier - the pick for rim joists, crawl walls and metal buildings. Open-cell is more economical for filling deep cavities where vapor drive isn't the concern. Foam costs more than fluff, so we spec it where its double-duty actually matters and use blown or batt where it doesn't - your quote will show that thinking.
Application is by trained crews with proper prep, ventilation and cure times - foam done right is inert and permanent; foam done sloppy is a mess with a warranty problem. We do it right.
Cured foam is inert. The care happens during application - our crews follow prep, ratio and ventilation protocols, and re-entry times are stated, not shrugged.
Sometimes - and often a hybrid beats it: foam at the rims and crawl, dense-pack in walls, blown attic. Best assemblies for the money; we'll design it.
Open-cell noticeably deadens airborne sound - a nice side effect in bonus rooms and offices.