Ecobee would be for a thermostat, correct? Integration wth Ecobee for everything except HomeKit, requires a cloud integration via Ethernet.
If your devices are already HomeKit capable, then the ‘Apple TV4’ HomeKit controller could be used to create automations that mix and match all of your HomeKit devices however you see fit (within the capabilities of what HomeKit automations offers.)
Using Zigbee and/or Z-Wave devices with HomeKit is where things get complicated quickly. As @prjct92eh2 mentioned earlier, Aqara is releasing a hub that is HomeKit capable and should, in theory, allow Aqara Zigbee devices to be easily ‘seen’ by HomeKit. They would then be able to be used in HomeKit Automations like any other device. I am not aware of a Z-Wave bridge to HomeKit that does not involve the use of a custom man-in-the-middle server solution like HomeBridge. Getting HomeBridge up and running is not terribly difficult, but is also not trivial or plug-n-play. You also need to have a Z-Wave controller that is supported by HomeBridge, like a SmartThings Hub or Hubitat Elevation hub.
As you can see, “Choosing a hub” is not a trivial decision. There are pros and cons in whatever you choose. Knowing what your long-term goals for home automation are will really help guide the decision-making process. Are you looking for ‘control’ of your home, or is home ‘automation’ what your looking for? Some platforms are more robust/resilient and perform quicker at certain tasks. Others offer for integrations, but suffer from a dependence on both your home Internet connection as well as the vendor’s Cloud Server platform.
Just thinking out loud… most home automation solutions revolve around one main automation controller, where the majority of rules/automations are executed. Popular choices for this are Apple HomeKit, SmartThings, Hubitat, Vera, HomeAssistant/HASSIO, etc… The list used to include Staples Connect, Lowes Iris, and Wink. Both Staples and Lowes have shut down their platforms, and Wink appears to be a sinking ship with its users jumping to alternative platforms that support the majority of their existing devices.
So, I guess we’re back to the question of “What would you like to accomplish with home automation?”
No matter how you answer that question, I believe that Lutron for lighting is never a bad choice, as it can be integrated easily with most every current home automation system on the market. Getting the PRO2 model of the Smart Bridge, just keeps all of your options open. I have replaced almost every wall switch in my home with Lutron Caseta, and I can honestly say that I have never had a single issue with any of these devices.
Hope this helps…at least it might generate some additional questions for you…