Insteon has been one of the most common X10 replacements. Later devices utilise both powerline signals and RF signals, in a simultaneously broadcast dual mesh system. As you may know from X10 powerline signal experience devices over 100-500' are known to opearte reliably and Insteon devices are all mesh simultaneous repeaters. The more devices you have the stronger the repeat signals get and the further they reach. This makes it the most reliable HA protocol ever seen by most. There are some people's environments that have too much electrical and RF noise to support well so it is not 100%. Most Insteon systems also support X10 so it allows you to use your X10 modules without and repeater functions so only within closer geographically located devices.
Insteon allows usage between devices without any central hub intelligence, if desired. Two switches and a lamp can be logically connected without any hub required and operate as if they were hardwired, without any perceptible delays.
However. The Insteon devices have become hard to aquire as the company basically drove itself into the ground with bad management and marketing. Now the remains have been picked up by an enthusiast crowd and we have big hopes for the future as the CEO appears to be engaged in fixing the problems they incurred in the past...number one...listening to your audience. Insteon is hoping to have many of their devices back on the market by the end of this year. Meanwhile tere are many dumping their devices cheaply as the end was thought to be near. My system has not been affected at all by some bad news. Most have no cloud dependence either.