The best replacement for tera is rift.

The best alternatives to tera are rated as following:
★★★★★  rift
★★★★  wow
★★★★  guild wars 2
★★★★  aion
★★★  neverwinter
★★  vindictus
★★  swtor
★★  raiderz
★★  dragon nest
★  giga
★  gw2
★  blade and soul
★  c9
★  ffxiv
★  jenna
  path of exile
  peta
  final fantasy 14
  aura kingdom
  eso
  tetra
  elder scrolls online
  diablo 3
  wildstar
  secret world
  world of warcraft

Your alternative for tera is not listed? Suggest!
Speaking about tera, one probably shouldn't forget about steam overlay.

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



Google Trends

Scale is based on the average worldwide traffic of tera in all years. Click on graph for more.
tera
rift
wow