In quantum magnetism significant efforts have been devoted to the search for new quantum states. In particular the Quantum Spin Liquid (QSL) state on the triangular lattice has attracted a lot of attention as it shows intriguing collective phenomena such as fractionalized excitations. We have synthesized a large amount (5g) of polycrystalline samples of four members of the Ba6R2Ti4O17 (BaRTiO) Seff=1/2 triangular antiferromagnets family, with R = Yb, Nd, Er and Y. Here, we propose to use neutron spectroscopy to determine the spin anisotropy of the effective S=1/2 triangular antiferromagnets of this family. The single-ion anisotropy is a crucial parameter to determine in order to confront the observed ground states to the theoretical phase diagram of the anisotropic triangular model, where QSL states have been predicted.