Here are a few answers to your question:
I think you'll find the general consensus is that granite is your best option, if you can afford it. It's durable and fairly low-maintenance, and probably has the best resale value.
I personally like Quartz since I cook a lot and have little ones at home so no time for maintenance. Granite for sure when they grow up and I cook less.
Granite continues to be the number one choice for counter tops, it is heat & stain resistant & does not scratch easily, the negative is that it emits radon in low doses. Quartz is the 2nd favorite, it is a little more contemporary in style, but excellent in performance as Yamini stated. Marble is rising in popularity due to the new sealers. In the past marble was a problem due to it's porous nature and stains. The man made composites are also a wise choice, less in price also.