I would think that ATC experience would probably be a bit more valuable than maintenance experience, even though (from what I have heard from ex controllers) the jobs are quite different. I suppose that, aside from actual dispatch experience, working in a place like airport operations would be considered pretty good. In general, on your resume you want to present a well-rounded profile that includes some indication of strong desire to work in aviation. To that end - pilot licenses, A&P licenses, and ATC experience all would help. Just my opinion.