The capacities of various interatomic potentials available for elemental germanium, with the scope to choose the potential suitable for the modeling of germanene (2D germanium) allotropes were investigated. Structural and mechanical properties of the flat (F), low-buckled (LB), trigonal dumbbell (TD) and large honeycomb dumbbell (LHD) single-layer germanium (germanene) phases, were obtained using the density functional theory (DFT) and molecular statics (MS) computations with Tersoff, MEAM, Stillinger-Weber, EDIP, ReaxFF and machine-learning-based (ML-IAP) interatomic potentials. A systematic quantitative comparative study and discussion of the findings are given.