Replacement door material

[Cyrano]

I'm replacing the exterior doors in an older home for efficiency, and because there was enough seasonal flex in the current frames and slabs that they don't easily close in the summer, and don't easily remain closed in the winter.

What are the pros and cons of steel vs fiberglass replacements today?

[GuitarStv]

They're both kinda similar in insulation value as long as you get insulated ones.  Steel doors tend to dent if struck very hard, fiberglass can crack (but won't dent).  Steel doors tend to be a bit stronger and are usually a bit cheaper.