The recent enhancement of the standard Refined Zigzag Theory (RZT), herein named the enhanced Refined Zigzag Theory (en-RZT), has extended the range of applicability of the RZT to angle-ply multilayered and sandwich plates. The aim of the present investigation is to assess the numerical performances of the en-RZT for the buckling analysis of angle-ply multilayered and sandwich rectangular plates under in-plane normal loads. The linearized stability equations are obtained using the Ritz method in conjunction with the principle of virtual work, by means of Gram-Schmidt orthogonal polynomials. In order to assess the accuracy of the en-RZT, buckling loads of angle-ply laminated and sandwich plates are evaluated and compared with the numerical results available in open literature. The numerical investigation highlights the high accuracy of the en-RZT in predicting buckling loads. The study contains a parametric analysis aimed to investigate the influence of various design parameters, such as plate aspect ratio, thickness, lamina orientations, in-plane load combinations and boundary conditions on the buckling loads.