it's your choice, both are bad for your health, although if you have dark chocolate then it's better for your health.
It is just chocolate.
if you call a peppermint a candy then a type of candy has chocolate and candy in it is those chocolates with the peppermint pieces in it.
Dark chocolate because it contains more cocoa and less milk, butter and sugar and cocoa is good for you, however, milk chocolate isn't made up of much cocoa but manely fats.
dark chocolate is better than you even when you might think that it's nasty!