The VTech DM221 audio monitor is the best choice in the category—it's consistently a best seller at multiple retailers, with thousands of positive customer reviews. Losing video is a major sacrifice, of course, but we could see this monitor being a good choice for parents of toddlers who are considering replacing a failing monitor, or people who want a monitor only so they can hear their kid crying out from a distant bedroom.
It may surprise you to hear that simply being able to last through the night, unplugged, with the display off, qualifies as exceptional battery life for a baby monitor. The Infant Optics was one of the only monitors in our testing that could easily do that, and then last a while longer the next day before needing a charge. (The manufacturer claims it lasts 10 hours with the display off—we got that amount of time off a full charge, even when checking the display intermittently.) This model also charges via a USB connection, which actually sets it apart from a variety of competitors, some of which use ineffective and inconvenient proprietary DC chargers or even disposable batteries.
If you sleep in the same room as your baby or live in a small enough space that you can always hear or see what your baby is up to, you probably don’t need a monitor. Otherwise, most parents enjoy the convenience a baby monitor provides—instead of needing to stay close to the nursery or constantly checking on your child, you’re free to rest, catch up on Netflix or get things done around the house during naptime. Monitors can also double as a nanny cam to keep an eye on your child and their caretaker.