The best replacement for grain size is ductility.

The best alternatives to grain size are rated as following:
★★★★★  ductility
★★★★★  porosity
★★★★★  hardness
★★★★  permeability
★★★  yield strength
★  cooling rate
  particle size
  annealing temperature
  small grain size

Your alternative for grain size is not listed? Suggest!
Speaking about grain size, one probably shouldn't forget about hardness.

Other search terms related to grain size and their ratings are:
★★★★★ hardness
You have in mind a companion for grain size and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of grain size in all years. Click on graph for more.
grain size
ductility
porosity