Best of breed in the OSX space
As a lover of "Tag & Rename" prior to my MAC days (and still retain that single app within Parallels — the only use for Windows on my MAC), TagR is the best and most functional I have found for OSX. Not laden with features, and missing some basic core functions like Search & Replace, however, for effective MP3/Mp4 tag renaming of large libraries (I have over 200,000 songs), TagR comes the closest over other OSX options. Simple functions, drag & drop.
TobySimkin about
Tagr