The best replacement for epoxy is polyurethane.

The best alternatives to epoxy are rated as following:
★★★★★  polyurethane
★★★★  polyester
★★★★  polyester resin
★★★  fiberglass surfboards
★★★  super glue
★★  resin
★★  urethane
★★  fiberglass surfboard
★★  urethane primer
★★  wood glue
★  glue
★  enamel
★  stain concrete
★  etching primer
★  urethane grout
★  sanded grout
★  paint garage floor
★  polyester surfboard
★  hot glue
★  jb weld
★  gorilla glue
★  self etching primer
★  2k primer
★  epoxy
  adhesive
  enamel paint
  polished concrete
  fiberglass resin
  fibreglass surfboards
  etch primer
  polyurea
  poly surfboard
  foam surfboards
  cement grout
  welding
  polyurethane surfboards
  resin surfboards
  regular grout
  poly
  fibreglass
  superglue
  oil filled coil
  poly surfboards
  polyester wood filler
  grout
  urethane coatings
  repipe
  pu
  chlorinated rubber

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

Other search terms related to epoxy and their ratings are:
★★★★★ aggregate
★★★★ fiberglass mat
★★★ graphite
★★ sawdust
★★ pea gravel
★★ pebbles
★ fiberglass
★ silica sand
You have in mind a companion for epoxy and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of epoxy in all years. Click on graph for more.
epoxy
polyurethane
polyester