My favorite was coming home to my garage door being open every now and then. Yeah, risky implementation...and I wouldn't have set that up if it weren't for my Visonic alarm system tempting me by having an X10 interface that allowed for SMS commands (cellular) to be sent to the alarm system to operate some number of X10 devices.
I loved the honkin big 240V cross-panel circuit X10 signal repeater that made my drier plug stick out an extra 2" or so. As I recall that thing wasn't cheap...but it fixed some of the problems getting signal around the house.
I don't trust ANYTHING to open or close my garage door. Had an aux relay on my Elk M1G alarm system set to open the garage door when a button was pressed on my fob. Came home once to an open door and disabled it and won't trust it again. Some things are better left not automated.
But Insteon is the superior evolution, and it can work with Hubitat with the aid of a bridge. I use it myself and it's one of the most reliable of anything I own. Hubitat automation with Insteon is top notch, and offers Lutron RA2 type integration at the cost of what you can expect from Z-Wave (but without the headaches).
Coincidentally, perhaps ironically, the best "budget" bridge was in fact... a 220V electric clothes dryer! Turns out some models created the phasing needed for X-10 to work across legs of your breaker box, just by being plugged in. I heard along the way that the bridging was somewhat hampered (no pun intended) whenever the dryer was operating, due to heating of the element (high resistance?).
I just want my x10 palm remotes to be received by Hubitat then I can do what I want with the received signal. I use my phone app to control everything (KASSA via Hubitat) but my wife is disabled and used to those little x10 remotes.
X10 can run concurrently with zigbee, zwave and wifi. Let her continue using her palmpads and incorporate the newer technology for things she may not need to control. There are zwave button controllers that can easily replace your palmpads if you want to totally dump x10.
Wow so glad I came across this thread before asking if anyone has developed an X10 bridge for HE.
I guess I'm in the minority but I still have a fair number of X10 devices in use for specific purposes. The wall switches were always awful but I still use a few outlet modules and a lot of the motion sensors. And I have a variety of door sensors running on DS10a receivers (which can work with any open/close device). The key was replacing the interfaces with those from JVDE engineering and using RF sensors from WGL (not sure if WGL is still in business). My X10 and X10 RF stuff has actually been quite reliable. However, I went with UPB for wall switches and still have a lot of those in place. I got rid of all the Insteon switches except keypads - no one has come up with a keypad that is as easy to label and use.
I have it all integrated with Home Control Assistant which supports just about every technology I know about and talks to HE via Maker API.
So right now I have in use X10, Insteon, UPB, Zwave, and Zigbee, Ecobee, IR devices, IP interfaces, serial interfaces. Client/Server mode.
As my UPB switches start to fail (after 10+ years) I'm replacing with Zwave mostly. And replacing sensors with zigbee. WIth the upgraded interfaces and receivers, the issue with X10 hasn't been reliability - it's been lack of 2 way communication and for the sensors, having to reprogram when you change batteries. (and also ugliness)
I got dissed for this on another thread but I like the palmpads! Having a dedicated remote at hand is often easier than unlocking your phone and pulling up an app and then navigating to the right place. I'm able to use the X10 remotes via other software I have integrated with HE - but it's going to stop being developed soon unfortunately.
Home Control Assistant (HCA). Been using it for years - not sure why it never got more popular - I think it's better than anything else out there at a very low price point. Tremendous power and flexibility. Built in visual programming, ability to interface with scripts, accessible object model, superb documentation, great support. Alas, it's a very small company and they've announced that further development will stop within a year, and support in about 2+ years. As will cloud functions (which are only needed for Alexa, LIFX, etc). Has a decent mobile app too. I plan to keep running it until it stops working.
A couple things in case anyone is still interested. There was a somewhat successful X10 integration with ST, using Node-RED and a RPI. I ran this until ST killed Groovy.
The reason I was willing to go to the trouble is because I have a huge inventory of Leviton 6343, 16383, HCM06 and HCM10, DHC Red Line PLC dimmers. These are some the nicest dimmers I've ever encountered, with a tactile feel far better than any GE or Zooz product I've used. And they have the following features:
Scene Control capability when used with DHC Scene Controller.
Multi-station manual and remote On/Off switching and full-range dimming.
Soft On/Fade Off brightness levels allowing extended bulb life.
Memory of last scene.
I'm just now migrating from ST to Hubitat. If anyone wants to work on a Hubitat/X10 integration I would be game to put these back online in my home, but this really only makes sense if the X10 device can be polled for status. The Leviton controls I just listed are all capable of 2-way communication, as they were natively developed for use in Leviton's Toscana Control System. My problem is I'm just a hack code writer. I can figure out how to tweak a driver, but I can't write code from scratch.
The Hubitat integration doesn't add devices to the hub, but it can control Insteon devices and listen to events from them. I have no way of knowing for sure if it would do what you need for X10 since I only own Insteon, but it might be a starting-point if you're not able to use it directly with X-10 devices.
Some additional discussions and resources , as X10 is a question that pops up every so often.