Under five hundred dollars you get a robot with laser navigation, a good map of your home and enough suction for hard floors and low-pile carpet. More and more models in this class have a self-emptying station, and the odd one even a station that washes the mops. What you usually miss: hot water for the mop, a camera that recognizes socks and cables, and extending brushes for the corners.
The list below changes daily with the prices. The order is our consensus of 5 test sources; the price is today's lowest including shipping.
Score: consensus of the positions in 5 test sources, 100 = top of every source. Every model on this list is recommended by at least one test source. The bottom of a top list is still worth half the points, and a model named by only one source cannot score above 50. Only models sold in the United States count. Method.