The best replacement for poly is varnish.

The best alternatives to poly are rated as following:
★★★★★  varnish
★★★★★  mono
★★★★  jc
★★★  lacquer
★★★  monounsaturated fat
★★★  mono solar panels
★★★  mono fat
★★★  mono solar
★★  nylon carpet
★★  nitro
★★  ucsb
★★  multi
★  steel wheelbarrow
★  mater dei
★  lakewood
★  epoxy
★  pvc irrigation
★  synthetic gut
★  tesoro
★  steel lawn roller
★  texas southern
★  grant
★  uc davis
★  bishop gorman
★  rubber bushings
★  fresno state
★  wood plantation shutters
★  mono solar panel
★  multifilament
★  trivex
★  palo alto
★  mono crystalline
  texas southern university
  corona centennial
  wood shutters
  clovis north
  uci
  ite
  kraft
  mono panels
  wichita state
  berkeley
  texas so
  jc better
  wichita
  monounsaturated
  mono unsaturated fats
  cal tech
  crespi
  high index
  glenville
  junior college
  bellevue
  li ion
  nyit
  beach club
  los alamitos

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

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



Google Trends

Scale is based on the average worldwide traffic of poly in all years. Click on graph for more.
poly
varnish
mono