For me, it's mostly cleaning supplies, I guess.

a Miele S8 Kona canister vacuum, about a hundred microfiber cloths (Costco is fine), pumice stones, bathtub cleaning brushes, dry mop, Bon Ami, citric acid, and good soft-rubber squeegees preferably by Ettore.

The vacuum is nearly a grand, but there's a lot less dust in the air and on furniture and molding inside the house. It's also quieter, has stronger suction than the previous Kenmore Progressive and Dyson upright, and doesn't leak dust, although it does heat up and exude a faint plastic smell, though all vacuums do that. It's just more obvious with this one because the smell isn't masked by dust and the influence of more noise. The air gets clean enough such that right after I vacuum and stride around the house because I want to breathe in the air.

The cloths I use to wipe wall, clean dishes . . . and so on. Never returning to cotton.

Pumice stones from Home Depot clean lime scale . . . toilet rings . . . and can abrade away calluses, assuming of course we're using a stone dedicated solely for that, and not cleaning toilets and such.

Bath tub brushes with nylon bristles, one for general srubbing, one to get into the grout and edges. Good to keep around the tub when I want to quickly clean up.

Dry mop by Rubbermaid with built in spray, filled with vinegar. The pH of vinegar prevents bacterial growth, so the mophead doesn't spread a half rotting smell along the floor. The mophead is a microfiber pad. Floors get nice and clean.

Bon Ami is a cleansing powder made from limestone and coconut surfactant. It's less hard than glass, so it doesn't scratch it, but has a strong abrasive action because of the fine particles. A good alternative to bleach and acid based cleaners (like Bar Keeper's Friend, Clorox) because it is less caustic on the skin and thus more convenient. It is really effective on grease/fat based stains, as long as they are on fairly smooth surfaces.

Powdered citric acid, bulk, for limescaled shower doors. "Weak" acid by chemistry, because it produces chemical buffers. Means its less effective than strong acids, but also less dangerous. Still, glasses/goggles and gloves. Scoop some up and dab a little water and spread across the glass. Then brush in circles to dissolve/emulsify the citric acid with water and the limescale. Then wait and wet as needed to allow the reaction to dissolve the limescale. Wash off, use a wet cloth to wipe the glass (to remove resultant salts, which make for murky glass), wash off again (pail of water), and squeegee--

Squeegees. 12, 14, 16 inches. Start with 12" for use in the shower to remove water to prevent clouded glass. In general use around the house a wet microfiber cloth to wet glass, then squeegee it off. Vertical strokes only downward, or horizontal strokes in one direction, or otherwise. Another cloth wipe up water that collects at the sides and bottom (where you squeegee the water toward). A squeegee pole, if you do high windows.

And a lot of plain heather blue and grey t-shirts are nice, too.