The best replacement for encoders is resolvers.

The best alternatives to encoders are rated as following:
★★★★★  resolvers
★★★  incremental

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

Other search terms related to encoders and their ratings are:
★★★★★ steppers
★★★ motors
★★★ stepper motors
You have in mind a companion for encoders and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of encoders in all years. Click on graph for more.
encoders
resolvers
incremental