The s9's D-shape is made for corners — and it backs it up with raw suction

The s9 is the oddball in iRobot’s lineup, and that’s exactly why it works. Instead of the standard round puck shape, it’s a D-shape — flat on one side — so it can push right into corners and along baseboards where round robots leave a gap. Pair that with the strongest suction of any Roomba and you’ve got a machine that attacks the two weak points of most robot vacs: corners and carpet. It’s also the priciest, so it’s not for everyone. But if your house has lots of carpet and corners, the s9 is the only Roomba that really solves both.