The Kingston Negroni is my favorite variation of a Negroni. It uses Smith & Cross Jamaican Rum instead of gin which adds a whole new layer of complexity to the cocktail.
Smith & Cross Rum is an overproof, highly flavorful rum from Jamaica. There are notes of exotic fruit and spice and a distinct funkiness from the use of indigenous yeast used in fermentation. It is 57% ABV (114 proof) so it can really pack a punch in a cocktail.
I like to use Carpano Antica Formula as the vermouth because it adds a lot of vanilla notes to the drink that complement the Smith & Cross. I find that the flavors of the rum help to make the bitterness of the Campari and vermouth less apparent, making this drink dangerously sippable.