© 2014 IEEE. This paper presents a systematic benchmarking comparison between optimal motion planners. Six planners representing the categories of sampling-based, grid-based, and trajectory optimization methods are compared on synthetic problems of varying dimensionality, number of homotopy classes, and width and length of narrow passages. Performance statistics are gathered on success and convergence rates, and performance variations with respect to geometric characteristics are analyzed. Based on this analysis, we recommend planners that are likely to perform well for certain problem classes, and make recommendations for future planning research.