"Can anyone who has a 16 gauge sink comment on whether it flexes when you push the bottom of it? i have an 18 gauge sink and it flexes a bit." It isn't the gauge of the steel; your sink is improperly mounted. It's probably a double bowl with no stanchion between the bowls and it's probably clipped or blocked in place. A strapped 20 gauge double bowl sink cannot budge as that would defy the laws of physics. If your sink is flexing, it's leaking. If it's leaking, it's unsanitary, creating bug habitat, and endangering any reinforcement rods in your top.

Here's a good thread with lots of opinions. Here is a link that might be useful: Thread about Stainless and Silgranit

I have not seen a brushed nickel sink. And you say you see them the most along with stainless steel which I agree are commonly available. Do you have a link for a brushed nickel sink? I cannot comment on a brushed nickel sink, but I can tell you that all stainless steel sinks will scratch regardless of price. You can have a sink grid in the sink which will reduce the possibility of scratches. But many people don't like the grids cause they are one more thing to clean and deal with, with nooks and crannies for gunk. Many people just shrug their shoulders at the stainless scratches, because eventually they will all blend into a patina and you won't notice them. Other than the patina, stainless steel is tops in durability, assuming you get a thicker gauge like 16-gauge, which, as it turns out, is not more expensive than the thinner 18-gauge sinks if you shop wisely. Check out Kraus sinks sold at Overstock and other websites. If you are worried about scratches, you might want to look at different materials of sinks like enameled cast iron or Blanco Silgranit. What size is your sink cabinet base? That may limit your choices.

We have installed Ruvati single-bowl kitchen sinks in the kitchens of our duplex; one unit is our home, plus a third one in a rental unit. I have never had a rust problem. I believe they're 18/10 stainless, which shouldn't ever rust. They are 16 gauge and well insulated. Love the sinks, but wish there was just a tiny bit more slope toward the drain, which might make them easier to keep clean. I am constantly sweeping debris from cooking and cleaning into the drain.