The best replacement for state machine is sequential workflow.

The best alternatives to state machine are rated as following:
★★★★★  sequential workflow
★★★★★  workflow
★★★★  rtos
★★★  flowchart
★★★  finite state machine
★★★  behavior tree
★★★  state pattern
★★★  event driven
★★  state chart
★★  sequential
★★  activity diagram
★  rules engine
  flow chart
  petri net

Your alternative for state machine is not listed? Suggest!
Speaking about state machine, one probably shouldn't forget about event structure labview.

Other search terms related to state machine and their ratings are:
★★★★★ event structure labview
You have in mind a companion for state machine and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of state machine in all years. Click on graph for more.
state machine
sequential workflow
workflow