What's the best alternative to spray foam insulation?

I have a 3100 sq ft house. Had a guy give me a quote for around $6k to do spray foam. He says it'll lower my energy bills (we usually pay $350/month in the spring and $800/month in the winter) and make every room in the house feel the same.

I have hesitations though: first off, I think spray foam is toxic and the gassing off will be dangerous. Secondly, I've read that it can trap moisture between the roof shingles and the wood (since there's no ventilation under the wood), and since we JUST spent $25k on a new roof (plywood boards and all), I don't want anything to happen to it for the next 25-40 years.

Is there a better alternative I can look into and get quotes for?