Brushless motors are the only sensible choice if you want a vacuum that still works like new in year three

This is one of those specifications that seems boring until you experience the difference firsthand. A brushless motor in a robot vacuum will maintain its full suction for years — I’ve got one that’s been running daily for three years and still picks up like day one. A brushed motor, by contrast, starts losing power noticeably after a year or so, and by 18 months it may need replacement entirely. The physical brushes inside wear down from friction, which is just basic physics. When you’re comparing two vacuums that look similar on paper and one has a brushless motor and the other doesn’t, pick the brushless one. You won’t notice the difference in month one, but you will in month eighteen.