In this study, the contributions of light scattering and extra-loss mechanisms to the total losses and to the differential mode attenuation of the guided modes are quantified for three different few-mode fibers. The tested fibers have the same modal content but different refractive index profiles, namely step, trapezoidal and parabolic. It is demonstrated that a trapezoidal index profile is a good compromise between low attenuation, low differential mode attenuation while maintaining large effective index differences between modes so as to reduce mode coupling.