Explorer for moving files and Tag and Rename for managing tags has proven to be the most flexible, most efficient and most powerful tools for managing tags.
I would love to have 1 tool to do it all, but MC can't handle it. "Part of a compilation" and "get album art" work so much better in Tag and Rename. I have the ability to look up album art and information on multiple amazon stores (by country) and it lets me choose the multiple versions of the album to get the data. If you buy a lot of CDs overseas while traveling, its great to have this flexibility. I can see the 7 different versions of the CD and pick the one that matches the one I have. YADB basically gives me one choice in most cases.
MC is great for making changes to individual files, but when it comes to the heavy duty work, there are better tools.