Two sinks that look identical on the shelf can be 0.5mm and 1.2mm steel. The thin one costs half as much and dents the first time somebody drops a sufuria in it.
For a rental or a back kitchen, 0.6mm is honest value. For a kitchen in daily family use, 0.7mm and above holds its shape. Fitted kitchens with granite or quartz tops use 1.2mm handmade bowls, undermounted, and those will outlive the kitchen.
Grade matters too. 304 stainless has nickel in it and resists the pitting you get from salty water and bleach. 201 is cheaper, slightly magnetic, and stains around the drain within a year or two.
Listen to the sink before you buy it. Tap the bottom of the bowl. A thin sink rings. A thick one with sound deadening pads underneath makes a dull thud, and that is the one that will not boom every time you run the tap.