There is no technique better than the other. In any case, the density gradient centrifugation process allows us to obtain cleaner samples, that is, with a reduced percent of sperm with poor motility and other cells.
Choosing the most accurate method depends on the preferences of each fertility clinic, sperm quality, the fertility technique to use...
Another option is to do a "mix" between the techniques described above. It would consist in using density gradient centrifugation and, with the resulting sample, perform a "swim-up" process. By doing this, we can obtain the best of the best.
Suggested for you: What Is Capacitation of Sperm Cells? – Definition & In Vitro Techniques.