What is the best product for cleaning a bathroom sink?

For longevity, the classic sink made of ceramic coated cast iron will last and last. (You can see some ceramic and cast iron sinks from before the U.S.Civil War in some of the Ante Bellum homes in Natchez, Mississippi)

Solid ceramic wash basins are good. But, after 30–30 years tend to develop cracks that can cause one to break off the support and go crashing if you fall against it in the night. (That is what initiated my bathroom renovations 12 years ago. Slipped on a still wet floor feeling for the light switch and broke the sink off the wall.))China Extrusion Blow Molding Machines Manufacturers

If you want to look really posh, you can go for carved marble. If you can afford for a sink alone what you can buy a small used car for, go for it.

If you want something that looks good now and is dirt cheap but will need replacing in five years you go for thermoplastic. (RVs and Mobile Homes usually come with such. They are functional but will start looking worn in a year or so.)

The current state of what you find at the big box hardware outlets in the U.S. runs to fiberglass. It lasts longer than molded thermoplastic and so many are ready to renovate and change things in 15 years or so anyway. (Fiberglass is prone to scratches over time but can readily be refinished and even have the color changes with an application of epoxy paint.)

That is my take on sinks and bathtubs… from an old fart that renovated about 12 years ago.

I replaced the sinks with stainless in the kitchen as the ceramic was chipped. New fiberglass wash basins in the bathrooms. But, I didn’t give up the old cast iron tub as the new ones aren’t available in a length where my 6′1″ body could recline comfortably. I’ve been happy with a refinish of a ceramic tub with a HVLP spray coat of epoxy paint to refinish. (Gad that early 60s peach color really dated the place… the tub is now eggshell white. The old wash basins and the kitchen sink were solid ceramic that had started cracking after decades of use.)