Muenster is an awesome cheese for hot sandwiches and burgers. Provolone is my favorite for cold sandwiches and snacking. Cheddar is my go-to cheese when I don't have anything better, it fills almost any role satisfactorily, if not superbly. The only time I really have Mozzarella is on a pizza. I know I linked this before, but
Dubliner cheese is a really interesting one I can find at the supermarkets around here. Very flavorful, good for a snack tray with fruits and crackers.