The best replacement for subfloor is underlayment.

The best alternatives to subfloor are rated as following:
★★★★★  underlayment
★★★★  concrete slab
★★★★  plywood
★★★  substrate
★★  osb
★  dricore
★  advantech
  finished floor
  sheathing

Your alternative for subfloor is not listed? Suggest!
Speaking about subfloor, one probably shouldn't forget about tile.

Other search terms related to subfloor and their ratings are:
★★★★★ tile
★ tar paper
You have in mind a companion for subfloor and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of subfloor in all years. Click on graph for more.
subfloor
underlayment
concrete slab