An antenna array of directional sensors offers more degrees of-freedom to improve the source localization accuracy. The originally sophisticated expression of the CRB turns into a factorized one at high SNR, perfectly suitable to derive an objective function that depends on the array geometry and the source direction PDF. Analytically untractable, optimization is conducted by systematic search for a two-sensor array. The so-optimized array has a finite accuracy in all directions, contrarily to fixed-geometry linear arrays, and a performance comparable to larger-sized fixed-geometry circular arrays, and so at all SNR levels