The best replacement for mt4 is mt5.

The best alternatives to mt4 are rated as following:
★★★★★  mt5
★★★★  ninjatrader
★★★  4pls
★★  ctrader
★★  m12
★★  emta
★★  trading station
★★  m11x
★★  st4
★  tradestation
★  futaba 4pl
★  ecn
  dx3s
  spektrum dx3r
  4pks
  mt6
  mx3x
  4pl
  fxcm platform
  metatrader

Your alternative for mt4 is not listed? Suggest!
Speaking about mt4, one probably shouldn't forget about fxcm.

Other search terms related to mt4 and their ratings are:
★★★★★ fxcm
★★★ oanda
★ ecn
You have in mind a companion for mt4 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mt4 in all years. Click on graph for more.
mt4
mt5
ninjatrader