The type of cheese you want to use is solely up to you here. A blend of Monterey jack, cheddar, and mozzarella is what you'd typically find in prebagged Tex-Mex cheese. You can use all of one cheese or mix and match them, but I would always suggest using a block of freshly shredded cheese over store-bought. Store-bought shredded cheese contains anti-caking agents which prevent them from melting well and can sometimes cause the cheese to have a grainy texture.
We love the flavor Italian seasoning adds to this quesadilla, however, you can certainly omit it if desired or substitute it with whatever seasonings you like. Try paprika or cayenne pepper to spice it up a bit. Using a seasoned or flavored cheese like jalapeno pepper cheese will add flavor all on its own.