The healthiest cheese to put on sandwiches is Mozzarella Cheese.
Other healthy cheeses that make great sandwiches are blue cheese, feta cheese, ricotta, Parmesan cheese, Swiss Cheese and Cheddar Cheese.
I like to use either sliced Cheddar Cheese, Swiss Cheese or the Mozzarella Cheese on my sandwiches.
If you want the healthiest cheese make sure you're not buying imitation cheese as that imitation cheese is not made from milk and is not real cheese.
The imitation cheese is cheaper but it's not real cheese and not as healthy for you.
So make sure you're buying and eating real cheese if you want the healthiest cheese for your sandwiches or for just eating the cheese in general.