Many smart people can come up with analysis on how long virus lives on this or that surface. The point is that stainless is easier to clean and doing so does not tarnish the material (unlike soap and water on leather). Sure virus particle may stay reactive on stainless laying out longer than leather. But if you are practicing the essential practice of washing hands and arms then I believe stainless to be the best. Or to be honest no watch or ring if getting fanatical.
Regards,
Kevin