Apple collects less data by default, and data is kept on the device whenever possible.
Apple HomeKit: HomeKit is the most restrictive of the three, but it's still the best option for iPhone owners. Apple’s tighter control over third-party certification ensures smooth operation for supported devices. You won't find as many HomeKit-supported devices as with Alexa or Google Assistant, but the major smart-home brands are covered. Apple's Home app is elegant and easy to use, devices are easy to set up, and its platform is the most secure. Apple collects less data by default, and data is kept on the device whenever possible. If you want to control devices when you’re away from home, you need a HomeKit hub device, such as a HomePod Mini, Apple TV, or iPad. Siri is also the weakest of the three voice assistants, though it's getting better.