What is the easiest material to clean with hard water for a non cleaning, non house proud family 
The bathroom sink seems OK and it's ceramic, I've cleaned it maybe once a month for limescale and it seems OK but there is still a build up I can't shift.
I have no idea what our down stairs sink is it's not stainless steel and again has a build up of lime scale that I've never been able to shift even with scrapping at it with a knife.
So for a new sink... What about a composite sink??
Or ridiculous? Ceramic?