A good answer is - Both.
There is no silver bullet to cybersecurity. Conventional approaches rely entirely on a single type of testing - either manual or automated web scanners - leaving business leaders in a difficult spot of choosing one way or the other for their products. While manual testing brings nuanced and intuitive strategy to the table, it could cause human-errors while taking several days to deliver results. On the other hand, automated tools that give instant results, do not promise the intuition that an actual human contributes. To add to the uncertainty, security testing vendors often position their approach as superior to the other, underplaying obvious shortcomings, jeopardizing entire products or businesses.