Natural, very hard stone that is mined from quarries all around the world. It is cut down to a manageable size and then polished to various types of finishes.
Because granite is a natural stone, no one slab is like another. This means your neighbor will never have the exact same countertop as you.
Depending on your style, there are many colors of granite that are more affordable than quartz. However, if you like a particular style or pattern, you may be in the same price range as a quartz.
For obvious reasons, mining granite can take a toll on the environment. Not only the impact from drilling, but transportation from various countries can add to the impact.
Man-made material that is typically known in commercial applications. It tends to have a smaller design pattern, but more recently can take on the look of granite or marble, allowing for similar look but with durablilty and stain resistant qualities of quartz.
Since quartz is actually harder than granite and therefore, more durable and scratch resistant. Although, neither are destructible. Granite is actually easier to repair should anything ever happen.
Quartz isn't porous like granite, so it's easier to keep your countertops relatively bacteria-free. Both should be cleaned with soap and water.
Quartz can be damaged by excessive heat, so using heating pads at all times will ensure the longevity of your countertops. Although it isn't recommended to apply heat to granite either, it is more tolerable since it is natural. Quartz should not be used outdoors since it does not tolerant the sun, so granite is the best choice for outdoor spaces!
What it all essentially boils down to is the look your are wanting, your budget, and how maintenance-free you are wanting your space. Let us help you decide what would best suite you and your space!