There has been research about the certification most requested by the industry market, but the analysis has continued to change over the different years, and the answer can vary by country and by role.
VMware's certifications remain still request and, in most cases, in the top 10-20 position.
Certification makes a difference by offering multiple benefits, including higher productivity, swifter troubleshooting, and fewer skill gaps.
For an example of some research on certification, see https://blogs.vmware.com/services-education-insights/2017/10/3-key-takeaways-2017-skills-salary-report.html.
Certification also provides indirect benefits, which can vary by the certification type and level. An interesting analysis can be seen in the blog post at https://blogs.vmware.com/services-education-insights/2017/11/%C2%ADbenefits-vmware-certification-6-key...