We present magnetization and ferromagnetic resonance (FMR) measurements on arrays of Ni nanowires grown by electrodeposition on self-organized nanoporous alumina templates. The study focuses on the measurement by FMR of the anisotropy of these systems and its correlation with the magnetization loops as the wire diameter (d) is changed in a series of three samples. The magnetization data indicates an easy axis along the wire for the d=35 and 55nm, changing into an easy plane for d=65nm (all samples have an average inter-wire separation D∼110nm). FMR resonance allows observing the anisotropy effects in detail and is consistent with magnetization measurements. Yet FMR shows a complex behavior in the large-d sample that can be interpreted as resulting from a prevailing easy-plane anisotropy with some portions of the sample with easy axis along the wires, thus unveiling an inhomogeneous character.