I'm currently in my second year of teaching English at the secondary level, and I'm wondering if it's better to pursue a Master's in English (I have a Bachelor's in English Lit.) or Education. Is there a strong advantage to one or the other in terms of professional development for teachers? I also see myself teaching at the college level someday.
Assuming you are in the U.S., a master's degree in English may qualify you to teach at a community college (but there are enough unemployed Ph.D.s in English that the competition is tough for those with only a master's degree). It would definitely not be enough for a regular faculty position at a four-year college, but it could be a step towards earning a Ph.D.
A master's degree in education could be a valuable credential in secondary education, depending on how your school system handles it, but it counts for nothing if you'd like to teach English at the college level. (Furthermore, it doesn't qualify you to teach in a department of education, which would require a doctorate.)
In general, college-level instructors are expected to have much more in-depth knowledge of their subject areas than someone teaching at previous levels of education. Therefore, it would seem imperative to have the strongest possible degree in the field in which one wants to teach (or a closely allied field). So, in this particular case, a degree in English would be more useful than education.
If "secondary" means "high school," the calculus changes quite a bit, as what is expected often will vary from state to state or even school district to school district. You should see if an education degree is required, or if a lower level of proficiency (such as some form of certification) is sufficient.
With regard to your professional goals, I would hazard the following:
A master of education can offer state teacher certification, allowing one to teach in public schools and abroad. This qualification is of utmost importance to public schools but of comparatively limited importance to private or independent schools. Nearly all public schools will consider the credentials equivalent for the purpose of pay increases, so long as both masters are regionally accredited.
In private or independent schools, a master in discipline will generally be given substantially more weight by hiring authorities than a master of education, unless the latter was earned at Harvard, Columbia, or other similarly prestigious institutions.
Teaching at university (and increasingly at community college) will de - facto require a PhD, unless you possess truly extraordinary, publicly acclaimed research or teaching experience, or you know the hiring authorities personally and they are disposed to offer you a position typically granted to PhD recipients.
A U.S. master in English will likely not be available by distance learning and may be extremely costly to pursue without a TA, which at programs of distinction would very likely be offered to PhD students. Certain DL options from the UK exist (I reference in particular Birmingham and Wales Trinity Saint David), but unless backed by a PhD from a leading university would be unlikely to lead to university employment in the U.S. except for adjunct or non tenured roles.