The best replacement for backerboard is greenboard.

The best alternatives to backerboard are rated as following:
★★★★★  greenboard
★★★  cement board
★★  wonderboard
★★  drywall
★  durock
★  durarock

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

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



Google Trends

Scale is based on the average worldwide traffic of backerboard in all years. Click on graph for more.
backerboard
greenboard
cement board