Background and Purpose White matter fiber tractography relies on fiber bundle orientation estimates from diffusion MRI. However, clinically feasible techniques such as DTI and DKI utilize assumptions, which may introduce error into in vivo orientation estimates. In this study, fiber bundle orientations from DTI and DKI are compared to DSI as a gold standard to assess the performance of each technique. Materials and Methods For each subject, full DTI, DKI, and DSI datasets were acquired during two independent sessions, and fiber bundle orientations were estimated using the specific theoretical assumptions of each technique. Angular variability and angular error measures were assessed by comparing the orientation estimates. Tractography generated with each of the three reconstructions was also examined and contrasted. Results Orientation estimates from all three techniques had comparable angular reproducibility, but DKI decreased angular error throughout the white matter compared to DTI. DSI and DKI enabled the detection of crossing fiber bundles, which had pronounced effects on tractography relative to DTI. DSI had the highest sensitivity for detecting crossing fibers; however, the DSI and DKI tracts were qualitatively similar. Conclusion Fiber bundle orientation estimates from DKI have less systematic error than those from DTI, which can significantly affect tractography. Moreover, tractography obtained with DKI is qualitatively comparable to that of DSI. Since DKI has a shorter typical scan time than DSI, DKI is potentially more suitable for a variety of clinical and research applications.