The best replacement for activex is directx.

The best alternatives to activex are rated as following:
★★★★★  directx
★★★★  dll
★★★★  com
★★★  form control excel
★★  javascript
★★  plugin
★★  applet
★★  dde
★  form control
★  form controls
★  java applets
★  plugin flash
★  java applet
★  form
★  ocx
★  applet java
  npapi
  javabeans
  adobe flash player 11 plugin
  ole

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

Other search terms related to activex and their ratings are:
★★★★★ java
★★★ javascript
★ internet explorer
flash
You have in mind a companion for activex and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of activex in all years. Click on graph for more.
activex
directx
dll