Advantages and disadvantages of mortar and pestle materials

Greetings,



I am trying to decide what kind of mortar an pestle to buy. I see they come made of ceramic, glass, granite, marble, and stainless steel.



I have eliminated stainless steel because I read metal mortal and pestle can spark and ignite flammable chemicals.



Which of the others is the hardest? That is, which can grind the hardest materials and not be ground by the materials.



Which is least affected by corrosives, acids and bases?



Which is easiest to clean? Does not stain? Is least porous?



Any other properties to consider?



Thanks