SpaceMarines are considered Hulking, but the Black Carapice takes away the enemies bonus to hit you. I can't believe people still are mentioning how Spacemarines are better, and not mentioning the Faith Talents. Now if you are just talking TT, then you are probably unaware that all sisters have access to faith talents now. And really for the TT that is how it originally broke down-SpaceMarines=Powerful individual units Imperial Guard= Super Armoured Vehicals/Artillary, and Sisters= Faith Talents, and exceptional special units.(Now I could be out of date since I have not played TT since 3rd ed, but that is how it seemed to break down for me.)
I think there needs to be more novels on the Sisters, it seems in the spacemarine books they are not depicted as well as they are in the TT codexes, and the opposite is true for the space marines, in the novels they seem to be a lot stronger then in the TT codexs.