I'm long time user of Domoticz and MySensors ().
Domoticz is robust, work really fine, scriptable ... but the UI is old web style, and the python plugin interface not really used (probably about to difficulty to not use async libraries)
I have discover HASS recently, i'm surprised by all the plugins and the simplicity to install/configure it. It use modern web interface, and the new LoveLace UI seen to be awesome.
But (there are always a but ),
The support of MySensors is limited: if i have good understand, i have the obligation of take all my sketch and add the code to send all sensors values at the beginning of the loop (just one time) and the code to confirm the value in the receive() ; but MySensors implement the ack and since i save the status of the sensors in the eeprom, the controller can do the same.
First, have i really good understand ? and if yes, do you plan to implement more the MySensors functions ? (i have tried to read plugin code, but i m not au good python programmer, so i can't help)
Ps: sorry to writing English like a french cow