you wouldn't need to, but if you had to pick one, which would it be?
Shadows and shaders.
Has the option of switching back to default, hinders performance only a fraction of what 3D studs would, compliments the build without hindering performance at a constant rate, complete user control.
3D Studs
Adds studs to each and every brick and would need to account for every shape, does not compliment the build as much as shaders/shadows, increases load time and download time by at least 5x.