Back to topic. As always, and especially with model steam engines, you get what you pay for. I like Bachman Spectrum steam engines, but for the price, I like IHC better. The offerings from IHC seem to be a bit sturdier, though with any steam engine, care must be taken when handling the units. A bent side rod or driver could be devastating.
And being steam engines they will be a tad more expensive that conventional diesel models as there is more tooling and more parts involved.
My favorite steam engines, other than my brass engines, are the offerings from Rivarossi(Red Box) and Broadway Limited(BLI). But,with grandkids playing with the trains, I wouldn't recommend them.
If you are looking for something a bit more "bulletproof", look at the Mantua or Mantua/Tyco offerings. The latter is built a bit more for kids to enjoy. The former is for older operators, most being cast metal.
A word of caution. These engines, steam engines, cannot tolerate a "cornfield meeting" with the floor or rough handling. Their drivers are totally exposed and WILL bend if dropped.