Whipped cream frostings are great, but they don't hold up for very long outside the refrigerator, which is something to remember.
Ganache is my particular favorite frosting for nearly anything. It doesn't take long to make, goes on easily and always looks smooth and finished. Plus, it's chocolate. Doesn't get much better than that! Chocolate frosting goes with nearly any flavor of cupcake: yellow, white, chocolate, marble -- you name it. A splash of rum in the ganache gives it an upscale flavor. Or, you can try peppermint extract, too. Ganache is a good choice for cake or cupcakes, either one.