I drifted into home automation, did not set out to do it, but to get around problems, I ended up realising smart switching was the way to go. I had a mother who would go wandering, and we were told unless she was sectioned we could not lock the door to stop her wandering, so we needed an alarm to tell us she had escaped, so we could persuade her to return.
We started with Energenie, but it did not do what we wanted as we expanded, so have ended up with a host of apps, but they all will work with google home, so we can, once installed, control with one app.
So a number of base options you need to consider.
1) Google Nest Mini or Alexa for voice control.
2) Android or iPhone.
3) Which central heating system.
Maybe the central heating is the system, which will dictate what else will work with it. So the big question now is geofencing and learning TRV heads.
I found geofencing with Nest and Energenie was not really going to work, the problem is the time it takes to recover, I found for the TRV to work I had to cheat, set the temperature to 22º at 7 am and then down to 20ºC at 8 am, or it would be 11 am before the room reached 20ºC, this clearly will not work with geofencing, where it will not swap from eco to comfort settings until nearly home. I seem to remember someone saying with Tado you can set distance, but that is not the case with Nest. And both Energenie and Wiser use IFTTT for geofencing, not tried to set up.
I found Nest Mini's could sometimes behave like mischievous little boys. Would turn lights off, then say it did not know how to switch them back on, not done this for some time, but not sure want to trust it with central heating on voice control, by time you have found it has not done as asked, it's a bit late, lights are easy to see if done as asked. Son tells me Alexa is the same.
I have moved from Nest Gen 3 to control central heating to Wiser, main reason is Nest wall thermostat will not connect to room sensors or TRV heads in the UK, only the US version does that. I have a Wiser wall thermostat but technically don't need a wall thermostat with Wiser, it can be controlled directly from the TRV heads.
As to lights, had 5 Energenie light switches, now down to 2, and I have moved to Tapo (TP-Link) that uses batteries in the switch, so no problem with lights staying on dim or shimmer when on. I also have one relay inside a lamp, loads of smart bulbs, and some smart socket adaptors.
But the problem is I find I have around 6 apps, and 4 hubs, OK all works with google home, but have to be set up with their own app. Had a problem with Energizer tried using their own app, but it was a relabelled smart life app, and could not run both together, once moved to smart life all worked OK.
Some bulbs with turn on slowly and turn off slowly, some have dusk and dawn, but the problem non seem to have all the options, so again one has to decide which features you want.