My first choice is Grantite. Because I love the look of it's natural color and pattern. Where as Quartz's has a uniform pattern.
Grantite and Quatz are very simular, they can be scratched, chipped and heat and water damaged under harsh conditions.
Grantite it needs to be sealed because of it's porosity where Quartz dosn't.
But if you are like me and love the natural look of stone then go for Granite. Below are 2 sites that gives you more information on the comaprison's between Quartz and Granite.