The best replacement for steppers is servos.

The best alternatives to steppers are rated as following:
★★★★★  servos
★★  elliptical machines
★★  ellipticals
★★  treadmills
★  exercise bikes

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

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



Google Trends

Scale is based on the average worldwide traffic of steppers in all years. Click on graph for more.
steppers
servos
elliptical machines