I don’t know how big investment you are planning. And what is the current state of your heating system. Old or new…
But if you want to get something out of it, then you would look for something with some AI/learning/weather forecast capabilities.
I used to have in my previous appartment a Nest thermostat. That was quite nice, as it has learned by the presence sensor what is the daily schedule of me and my wife. It was working fine for me, but that was years ago.
I use Wiser TRVs around the house now, as I couldn’t replace my central unit. I have wrote a DH for them, but I couldn’t fine tune them last winter and the DH has a lot of work to be done on it too. Maybe I missed the point, but I couldn’t find a way to give the learning curve to the Smartthings setup. It is great that I can turn on heating on the radiators when I am in the way home, and the house warms up, but you might want to have that already learned by a complex solution.
All system has its pros and cons. If you can do, get one with a central unit and a thermostat plus separate TRVs, if your heating system hasn’t got zones already.
Central unit controls when you need heating, and its great if you can control hot (domestic) water too, if you have a hot water cylinder.
Thermostat provides feed to the central unit, needs heating or not, and can provide status heating or only circulating.
TRVs are the same as the thermostat, but they can shut off the radiator when the temperature reached the level. And they can tell heating is needed or just circulation.
And the state of your current heating system. Make sure you have decent valves on the radiators. Old and stiff valves will make the whole thing just a waist of money. And of course check that your valves are compatible with the TRVs. You can get plenty different adapters if needed, but you need to know what you need exactly.
A new condensation heater can save you good money or just cleaning out the sludge from the radiators if they are old.