Most people like to run their robotic vacuums when they’re not home, so that little critter can do its work without getting underfoot. But sometimes you’ll want to run it when you are home, and, since it takes a while to do its job, you’ll want a robot that can vacuum quietly.
In our research (as well as a little personal experience), the brands Eufy, Ecovacs, and iRobot (Roomba) are generally very quiet across all models. Eufy in particular is mentioned by many to quietly go about its business so you can watch TV or talk on the phone or let your baby sleep. However, the Roomba line of robot vacs has a long history of being very effective at the cleaning itself, with few complaints from its many purchasers. Combine that with its quiet nature, and that may be the best choice.