Both will stay cool to the touch but marble is much softer and stains more easily than granite. Not a reason to not go with marble but just a consideration. I have thick travertine marble in my family room installed in the Versailles pattern and I love it. It does get dirty but I feel it adds character to the space. We get it steam cleaned every few years but luckily it doesn't come out perfectly clean.

As Skydell says, both will be cool to the touch. Marble is softer and more prone to scratches and etching. If you're looking for an easy care stone, granite is your best option. We generally recommend marble for lighter use areas such as bathrooms. However, as long as you know what it will take to maintain a marble floor, and are ok with the "patina" that it will develop over time, it can be a gorgeous option as well.