The gauge of the metal and construction is important in stainless. A heavier gauge is better. you will see gauges ranging from 22g to 16g as I recall. A smaller number means heavier steel. The lower number the better. A heavier steel will bean less dents and it will also be quieter. Additionally better sinks will have a dampening material attached make the sink less klanky.
Also there are different qualities of stainless. If a magnet sticks to it its lower quality. "Most stainless steel sinks will come in 300 series stainless steel. Type 304 is the most common and is of good quality. Type 316 is marine grade quality, and is more resistant to corrosion than type 304. Typically, this type of stainless steel isn't found in kitchen sinks, rather, it is used in industrial sinks that might be exposed to chemicals
The other type of stainless steel you might find in sinks is type 430. This is not as good as 304 or 316. Type 430 corrodes easier than 300 series stainless steel." from http://boards.kitchens.com/eve/forums/a/tpc/f/2021067581/m/9771027333