The best replacement for ie8 is ie7.

The best alternatives to ie8 are rated as following:
★★★★★  ie7
★★★★★  ie9
★★★★  chrome
★★★  firefox
★★  google chrome
★★  ie10
★★  ie6
★  ie80
★  ie11
★  ff3
★  firefox 3.6
★  ie9 css
★  ie9 compatibility
★  firefox 3
  ie9 performance
  w3
  firefox 3.5
  ie8i
  tf10
  shure se535

Your alternative for ie8 is not listed? Suggest!
Speaking about ie8, one probably shouldn't forget about bing.

Other search terms related to ie8 and their ratings are:
★★★★★ bing
★★★★ xp
★★★★ windows 7
★★★★ compatibility mode
★★★ add ons
★★ html5
★★ ie10
★★ chrome frame
★ xp problems
★ sp3
★ ie9
★ ie7
★ ie6
★ vista
xp sp3
You have in mind a companion for ie8 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ie8 in all years. Click on graph for more.
ie8
ie7
ie9