The best replacement for solubility is temperature.

The best alternatives to solubility are rated as following:
★★★★★  temperature
★★★  miscibility
★★★  ph
★★  concentration
★★  dissolution
★★  ksp
★  solubility product constant
  particle size
  saturation
  solubility
  solubility product
  organic compounds
  isoelectric point
  insolubility
  molar solubility

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Speaking about solubility, one probably shouldn't forget about ksp.

Other search terms related to solubility and their ratings are:
★★★★★ ksp
★★★ common ion effect
★ polarity
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solubility
temperature
miscibility