I prefer imperial stouts. Most have hints of dark chocolate, coffee, and sometimes dark fruit, esp the super high gravity ones.
As for breakfast/coffee stouts, there are a few really good ones, and many that miss the mark. Hard to beat Founders Breakfast Stout. Some good local ones too from Evo and RAR. Flying Dog's coffee Porter is pretty good. Its the Kujo, which was originally an Imperial coffee stout, and it was excellent. Sucks they stopped making it.