Upon having made use of relative energy, relative polarizability and relative harness as three descriptors of relative stability, we test their behaviors in the description of the lowest energy isomers of all-metal clusters MAl4- (M = Li+, Na+, K+, Rb+, Cs+, Cu+, Ag+, Au+). It has been shown that the stability of the pyramidal isomer decreases with the addition of atomic number. Due to this reason, finally the planar isomer of the AuAl4- cluster is more stable than its pyramidal isomer. Compared to the minimum energy principle, the minimum polarizability principle is worth recommendation in assessing relative stabilities of isomers. (c) 2007 Elsevier B.V. All rights reserved.