I usually just use soapy water to clean my quartz. In the bathroom I use a citric acid (antibacterial) spray. Quartz isn’t as delicate as natural stones, but mine has never needed anything harsh. My sink is a Blanco fire clay. Use soapy water and a blue Scotchbrite on a daily basis and borax once a week to clean up any stains.

I use dish soap and fiber cloths.

Me too, just a small amount of dish soap on a damp cloth, paper towel or plain sponge (not an abrasive scrubby sponge), then wipe up - though I make sure the dish soap is not colored (like Palmolive is green, so not that, but some of the natural dish soaps at Whole Foods, or Mrs. Meyers, and some others are clear).

Soap and water, but when I’m cooking with raw meats and stuff like that I like to use a disinfectant spray afterwards. I’ve always used Method. I’ve had different quartz in kitchen and bathrooms for years and never an issue using this.