to name only one is impossible!! I like sooo many and they all serve different purposes!
We're cheese fans here... in fact we played 'desert island cheeses' recently and tried to work out which 5 we'd take to a desert island.
And the 5 would currently be...
a good strong cheddar (so versatile!)
roquefort (again versatile, brilliant in cooking)
parmesan
buffalo mozzarella
a nice tomme de savoie
that 5th one can change by the day though!