Definately Dunkin donuts. But beware of their brand that the grocery stores sell...it's not even close to the coffee you get at the donut shop.
I'm a big home brewed Folgers fan, too tight to pay top dollar for something I can make for pennies at home, I guess.
My favorite coffee is the cheap nasty instant stuff we drink while tent camping, on hunting and fishing trips. It's kind of nasty, but one taste of it puts me right back in camp.