You can control the Arlo via multiple platforms, including Alexa, HomeKit, Google Assistant, and IFTTT. The camera itself can work wirelessly off a rechargeable battery for several hours (which no other monitor we’ve tested can do), and it can track and chart several days’ worth of temperature or humidity in a child’s room. You can set it to notify you if it detects unusual temperatures, humidity levels, or “air quality,” a VOC measure the Arlo Baby manual (PDF) suggests you alleviate by either opening a window or removing the source of the VOCs. (Our also-great pick for the best air purifier is one of the few that actually does genuinely eliminate VOCs, but it ain’t cheap.) If you find that the notifications are too frequent, you can adjust what’s triggering the alerts (by raising the threshold up to 80 ºF, for example, if you don’t want a notification telling you it’s too hot at 76 ºF). You can store video from the camera online, but in six years of parenthood we’ve never once wanted to review baby monitor footage.
The features we focused on were those we thought either increased the performance of the monitor or made it more user-friendly for parents and increased the odds of getting good quality sleep. We looked for monitors that have sound activation that keeps the parent unit quiet when the baby isn't crying, so parents can potentially fall asleep faster because they don't have to listen to white noise. Some of the monitors were so loud, even at low volumes, that the white noise might keep light sleeping parents awake; this defeats the purpose of having a video product to begin with. We also liked the models with screens that automatically "wake" and/or go to sleep.