I am a high school math teacher and am going to get my masters. I don't know whether to get a masters in mathematics education or just a masters in math. Which would look better to prospective districts? Do they care what type of masters you have or just that you have a masters?

Yes, I am currently in my 6th year of teaching high school math. But if I want to get a math teaching job somewhere else, wouldn't it be better if I got a MS in a math related field?

One can never go wrong adding a master's in SPED, ESL, or something like Reading Specialist or Literacy. And yes, that is about the order that I believe would be valued as additional education given that you are already certified in math.

The primary reason for getting an advanced degree in your area of study would be if you wanted to teach on the collegiate level (my M.Ed. would only let me teach education, not English). The other reason, of course, would be if you truly enjoy your subject matter. I'd say go for the combined degree.

In my opinion, it just depends on the purpose for your masters. I got my Masters in special-education because it topped off my salary points and I already had most of the credits from my credential program so it was very affordable. If you want to get a masters to make yourself more hireable in a district, then I would get a masters in an area that might go well with your subject matter. For example, if you had enough credits in physics or chemistry, you could probably add on a credential which would make you more hireable. I don't necessarily think getting a masters in an unrelated area like special education would make you more hireable to a district. They want to see that you can either teach additional subjects, or that you are an expert in your own subject area. Adding onto this idea of being more hireable, I think, if you want to stick with math, the masters in math education would be appealing to a hiring committee.

Assuming you were some variation of a math major as an undergrad, you already have the credential that you'd need to get hired by another district. Having a fancier math degree won't help you any more. Look for something that gives you professional flexibility.

The OP was going to get an advanced degree regardless. I was commenting on the type of degree (core subject vs. education or another specialty).

Thanks to my alternative certification program I already had 15 hours of graduate credit in education. Thus, I went ahead and finished an M.S. in education and simultaneously took 18 hours of graduate biology; I already had a B.S. in biology. Since this qualifies me to teach junior college and dual credit classes I've never had a problem getting hired. If you want the extra math classes, then go for the M.S. in math. I doubt an M.S. in math education will limit you any if you have 18 hours of graduate math credit.

In my experience, the math ed degree will be easier than the math degree. The math degree may make you more marketable in other fields should you ever decide to leave teaching. Both degrees will probably move you up the salary schedule the same. If I were in your position, I'd do the math degree. I have a degree in my content area, and I think that it has given me a better handle on my content than I would have gotten with a different degree program.