In this study, three different tool pin geometries were studied for friction stir welding (FSW) of AA 6061-T6 to identify the best tool geometry in terms of the final weld properties. In this regard, tool rotational speed and tool traverse speed was assumed as input process parameters. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, yield strength, elongation and hardness, hybrid approach combining TOPSIS (Technique for order preference by similarity to ideal solution) with PCA (principal component analysis) method is proposed. An analysis of these optimized results for each tool geometries shows the taper threaded tool provides the highest properties. A confirmation test was also carried out to verify the optimized parameter for all the tools and they are found to be within an acceptable limit. Further, more efficient torque and force behavior were obtained for the taper threaded tool.