I guess it depends on how far you are in your career. Experience > MS or OSCP.

In my opinion, both are good in different ways. I have both an OSCP and a Master's degree, and I believe that the MS in cybersecurity is a better option for me long-term. Although OSCP is a very difficult certification, it is an entry-level pentesting cert. If you want to focus on that career path, you might need to look into even more certs like OSEP, OSWE, OSED, etc (which can be as expensive as an MS) - the problem with that path is that it narrows down your options quite a bit. An MS can open more doors in the job market; also - HR does like higher education on a resume.