The following two examples are hypothetical, but have a possibility of both becoming real (I'm a recent graduate with no CS work experience).
In both situations I would be going for my Masters in computer science.
A: I work for a pretty well-known insurance company writing software. They pay for me to go to school, and the school I would be going to does research in fields I'm interested in (though, with a full time job, I'm not sure how much research I'd be able to participate in), but they are not ranked highly (in fact, I can't find their ranking at all).
B: A decently ranked school (top 75) offers a research or TA position that covers tuition and a stipend. The school does research in areas that I am interested in.
In both situations tuition isn't a problem. The benefit of A is that I get work experience, but the school isn't highly ranked in CS (although it is quite well-known for other majors) and I'm not sure how much research I'd be able to participate in while working full time. With B I would get to do research, and the school is more well-known, but I would forfeit work experience.
If my ultimate goal is to end up working for a high-end software developer (Microsoft, Google, Apple, etc.), would option A or B be better?