If you are just looking at it from getting a better paying job perspective, then you will advance further by taking a lucrative job. However, if you are more motivated to broaden your knowledge then a masters is a good choice.
I know some management consulting firms like applicants with advanced degrees, but typically in cs/business not pure CS.
Even then, I might recommend getting your foot in the door and hopefully getting your employer to pay to continue your education.
The only other motivation that comes to mind would be a burning question you needed to research and answer for yourself. Perhaps though that would be motivation to explore a PhD rather than a master's.