Dad’s short answer: Five, in order: brush head design, filtration seal, bin capacity, serviceability, and how it's stored. Everything else — suction numbers, screens, app connectivity, attachment count — is a tiebreaker.

The five that matter

Brush head design first, because it does most of the cleaning. Motorized, anti-tangle, and suited to your surfaces.

Filtration seal second. A sealed system with a decent filter keeps fine dust out of your air. Without the seal, the filter grade is marketing.

Bin or bag capacity third. Too small means emptying mid-clean, and every emptying is a dust event. Matters most with pets.

Serviceability fourth — whether the brush roll comes out easily, whether filters are available, whether the battery is replaceable. This decides whether you get three years or ten.

Storage fifth, and nobody lists it. A vacuum that's awkward to store gets used less. A wall mount, a self-standing design, a retractable cord — all sound trivial, all change how often the machine comes out.

What you can ignore

Raw suction numbers, past a reasonable threshold. Same marketing race as every other category.

Screens and app connectivity on a vacuum. You're holding it; you don't need a phone.

Attachment count. Three tools you use beat eleven that live in a box in the closet. The ones that earn their keep are a crevice tool, a dusting brush, and a small powered head for upholstery.

Weight specs quoted without context — a light machine that's badly balanced feels heavier in use than a heavier one that's balanced well. Pick it up if you can.

Dad’s Take: Brush head, seal, bin, serviceability, storage. Get those five right and the rest is decoration.