MusicBee would be just perfect for my needs. It allows to attach all types of tags (enumerated as well as free text) to a file. It allows me to navigate in my hierarchical folder structure (which Calibre doesn't allow) and its has the column browser. And it is fast!
I tried other tagging applications, e.g. TagSpaces, Tabbles. They all lack free text tags and a columns browser and feel a bit sluggish compared to MB.
In the other hand, i do not all of the enhanced document management features as collaboration, workflow, version and change management etc.. That's what makes them so expensive.
So all i would need, is MusicBee not to restrict the file types and to open files based on the Windows file type associations.