Depends:
For salads I usually go feta, or a sprinkling of parmesan.
Parmesan for pasta, mozzarella for pizza, definitely.
Cream cheese mixed with chives for crackers.
For sandwiches I usually go with Swiss or hot pepper jack cheese.
For a quick quesadilla, I just slice some Monterey Jack in between two flour tortillas and nuke it for a minute and serve with sourcream with chives and salsa.
Gouda, emmenthal and stilton are great with cold cuts like salami and paired with wine.
And yeah, if I got nothing else to do I buy a 10 pound bag of frozen processed cheese and munch away like every single American.