While I like the look of the Tado thermostat and would like to control individual radiator valves from my phone, the accessibility of the Nest and the intuitive nature of the physical interface made it by far the best choice for me. If I wasn’t caring for my sight-impaired elderly mother I’d have other options but the connection between the thermostat and carbon monoxide detector would still make Nest a pretty compelling choice, I think. That it doesn’t work with HomeKit is a non issue for me. Although I do sometimes use Siri to switch lights on and off, I’m not sure I’d ever really use it for heating (most of my interaction with the thermostat is to switch it on or off remotely) and it’s certainly no hassle to use the Nest app.