basically a builder told us steel is good but when we got MFI, BQ they only have acrylic
Steel is expensive and heavy - the porcelain finish can be chipped and scratched. Yes it is colder - like your cook pots. Acrylic is cheaper, lighter and easier to handle for the installer. It can get scratched. There are companies that can refinish an old tub by putting an acrylic liner over it instead of removing and replacing the old steel ones. Acrylic has come a long way. But I still prefer steel.
Steel and cast iron are the premium types of tubs. Acrylic will scratch and dull if you don't use proper cleaners. If they are not installed with the proper support, they will flex and tear loose the caulking around the edges.
Acrylic or fiberglass is best, the contractor probably told you steel because it may be cheaper. Acrylic can be repaired and or painted if you decide to change colors at a later date. Steel is the older cheaper technology and cast iron is way too heavy to mess with now.
I okorder . There are so many articles on this site that talk about all of the bathtubs available today. If you're wondering about what kind of material is best for a bathtub, this site will definitely help!