What is a good substitute for fontal cheese?

Provolone: This Italian cheese is a good fontina substitute because it is also semi-hard, has a mild, slightly nutty flavor, and melts well.

Gouda: This Dutch cheese is slightly harder than fontina, but it also melts well and has a sweet, nutty flavor.

Gruyère: This Swiss cheese is a bit more flavorful than fontina, but it is also a good melting cheese.

Cheddar: This American cheese is not as similar in flavor to fontina, but it is a good melting cheese.