The links you've already provided (especially the second one) are quite good.
The top journal, I'd say, is the Journal for Research in Mathematics Education (JRME).
Depending on the content of what you wish to publish, it may be that a journal about education (not specific to mathematics) or one about psychology or cognitive studies (again, not specific to mathematics education) would be viable.
One option would be to look at where prominent mathematics educators have published; for example, you can find some of A Schoenfeld's recent publications here; some of D Ball's publications here (CV pdf); or, more generally, by searching for individuals on Google Scholar.
A lesser known option is the Journal of Mathematics Education at Teachers College (JMETC). The next issue has as its focus post-secondary education, so it may be a good fit for an article on undergraduate mathematics pedagogy. A link to the JMETC page can be found here.
I might note that, despite its relative newness, the JMETC has featured some well-known names in mathematics education: H Burkhardt, HP Ginsburg, C Greenes, J Kilpatrick, HO Pollak, A Schoenfeld, E Silver, WF Tate, U Treisman, and HH Wu.
I have listed some of these individuals' names, since they are generally good people to search for in order to see where else they have published recently.
(As for my own reading: I really like Math Horizons and the American Mathematical Monthly; I think the Mathematics Teacher is a good education-specific choice, too.)