I am using Tado in combination with Google home and Smartthing / webcore
I prefer HomeKit which I have voted for but I am also planning to implement Athom Homey and probably also Home Assistant. It would be great to see more support for these by Tado as well.
I am actively using Home Assistant and Node-Red for controlling Tado. It works pretty well but I would appreciate official API to be finally published.
I have tried repeatedly to set up Homekit with Tado, but Homekit doesn't recognise the Tado bridge. It works well with Alexa, so I'll have to stick with that.
I have used Alexa and google, but I try and avoid using any manual controls. Better automation should mean I never need to manually control, via app or voice.