The affordable Defiant Smart Wi-Fi Deadbolt is easy to install and supports multiple unlock methods, but don't expect it to interact with many of the other smart devices in your home.
The Yale Assure Lock 2 is a style-minded smart lock that makes it easy to go keyless and manage access to your front door while offering interoperability with many popular third-party smart home platforms.
The Bluetooth-enabled SwitchBot Lock seamlessly adds smart capabilities to your existing lock hardware, but you have to buy a separate hub to access all of its features.
The Level Lock Touch Edition supports HomeKit and several unlock options, including key cards, but it lacks Wi-Fi and doesn't work with many other third-party services.