Ecovacs DEEBOT T80 Omni

It empties into a 3 L bag and holds 4 L of clean and 2.2 L of dirty water, and it cleans its own base, so most homes go weeks between upkeep.

The robot is 3.8 inches tall, so it slides under most sofas and cabinets, though very low furniture may be tight.

It clears obstacles up to 20 mm, so it handles standard door sills but may stop at taller thresholds.

It washes the mop with 167°F hot water rather than auto-dispensing detergent, so you add cleaning solution yourself if you want it.