Both options are great options. Obviously, either way can further your career, so you should be asking which is a better fit for you. For example, ask yourself

Both options are great options. Obviously, either way can further your career, so you should be asking which is a better fit for you. For example, ask yourself - would you enjoy doing a PhD? If you wouldn't have fun, then don't do it. A second question is - what careers would make you happiest later on? If those careers don't require a PhD, then consider not doing one. Also: Are there multiple CS research topics that would interest you? Are you self-motivated and good at working on long-term projects? Are you happier implementing things or thinking about how to implement things?