August's Doorbell Cam Pro is a hardwire-only smart buzzer. For $199, £155 or AU$265, you get live streaming, two-way talk and other key doorbell features. This model also works with August's other smart home products, such as its HomeKit-enabled Smart Lock.
Nest's Hello won't be available until early 2018, but this smart buzzer has a lot of promise. Not only will it offer HD live streaming and motion alerts, the Hello should also come with Person Alerts and optional Familiar Face Alerts (with a Nest Aware subscription).
While Person Alerts notify you when the camera thinks it sees a person, Familiar Face Alerts will tell you who it sees if it recognizes the person from a saved database of friends, family and other folks who regularly visit your home.
Ring's $249 (£195, AU$325) doorbell is a pricier DIY buzzer. But there's a big potential benefit -- this hardwire-only model is slimmer than most smart doorbells we've tested. That means it's way more likely to fit on that narrow doorframe where your existing wired buzzer is currently installed.
The $199 (£155, AU$299) Ring Video Doorbell 2 is a very versatile device. Not only does it offer live streaming, two-way talk and other expected features. This 1080p HD buzzer can either be hardwired or rely on a removable, rechargeable battery.