As a self diagnosed chocoholic, I cannot just pick one. It really depends on my craving for the time. But if I were to name a few of my fav's,they would be: Valrhona dark chocolates, Theo 45% cacao milk chocolate, Green and Blacks Butterscotch and Burnt toffee, Lindt Caramel Intense, Toblerone milk(the large bar) Galaxy Caramel, Cadbury's Old Gold 70%, etc
I recently tried some chocolates from Patchi, there new range, and found them to be quite yummy.
Oh and Jeff De Bruggs does awesome chocolates,sold loose.