You have worked with mobile application development and data science and DevOps are three very different fields.
Both DevOps and Data Science are amazing career paths to choose from. Both of them have a huge scope and high paying available jobs.
A better question would be which of these would be a better career path for me?
Data Science has a lot to play with data, algorithms, and statistics. On the other hand, DevOps has a lot to do with infrastructure and automation. Dealing with Networks, Server databases and a lot more.
You need to decide what kind of work excites you and go ahead with it.
Career pathwise, both are really good. Check articles out for better understanding: