Quesadillas can be made with many different types of cheese. For this recipe, we recommend a Monterey Jack with Jalapenos. It has good flavor and melts well. Cheddar cheese is a good alternative because it's also flavorful. If you can find it, a Mexican cheese like Oaxaca is more traditionally used in quesadillas. It tastes similar to a Monterey Jack cheese and melts well too. While Mozzarella melts well and is easy to find in the store, we found the flavor a bit too mild to be our favorite.