Samsung NaviBot Silencio SR8895
This is the easiest of all robot cleaners to operate, and an ideal first step. A large remote control unit lets you tell the Silencio (HK$6,000) to leave its recharging dock to clean, and then return. The Silencio sweeps dust from the sides of rooms and furniture using side-mounted brushes, and its seven obstacle sensors mean that it rarely touches the furniture. However, it's not powerful enough to get over all the obstacles (such as thick rugs) or leave a room totally clean. It could be used regularly to keep dust at bay, but it won't replace a manual vacuum cleaner.
iRobot Roomba 790
A more powerful machine, the step-up Roomba 790 (HK$10,000) is capable of getting itself over, past or around stiff carpets, shoes and other detritus. It has cushioned sides that allow it to be a touch more cavalier about bumping into walls - which makes it better at cleaning those hard-to-reach parts of rooms. As well as picking up more dirt, the Roomba is quicker and more precise than the others.
Neato Robotics XV-15
Equipped with automatic timers and laser mapping technology, the XV-15 (HK$3,800) risks anthropomorphism by being one of the few robot cleaners to attempt communication. The XV-15 announces what it's doing, finishing up with a cheerful "I've finished. Heading back to recharge." In terms of cleaning, it's the second best here, although the XV-15 is particularly good at cleaning along walls, where it uses its straight-edged front to sweep most effectively. This vacuum cleaner isn't troubled by obstacles.