Accents I really give a pass. Aradesh, Loxely and Morpheus do come to mind. It's never really bothered me as it always came down to their character and writing. Morpheus to me seemed more menacing because of his accent. Aradesh, more kind, and Loxely, a derpy oversight but made him more like the Robin of Loxely, good for a giggle I suppose. Though Loxely is one of the weaker moments of Fallout for me. Same for the Lieutenant, made him more menacing. Fallout 2 you also had Sulik but not sure where his accent came from outside of the whole they're "tribals" thing but still gave him some flavor at least. Seemed a little Rasta for the area but is also a possibility. Accents for me at least. Not all that important to me but have only run across two npcs with non Bostonian accents, Curie and Cait.
Edit: There are American and Bostonian accents.