About a year to 18 months ago, I spent a couple of months comparing various players, which ended up as three weeks or so comparing MM and Helium (7 I think). I was looking to start the process of putting a large proportion of a medium-sized collection (approx 1400 albums/discs) on to PCs.
I am different to most users (not all) in that a majority of my collection is classical, with about 500 Rock/Pop/World etc, and 100 Jazz. I had already realised that iTunes and WMA and others can be ok for the latter two categories, but were appalling for anything more than a handful of 'classical' albums. MM and Helium seemed to offer the flexibility to organise these categories differently. However, I could never (in my free month) get Helium to organise my collection in two totally different ways, whereas, in the same period I did manage this with MM.
So, to anyone reading this who also has a very varied music collection which includes a large amount of classical, I would say that MM is the ONLY software player/organiser that will do what is needed. I looked at almost all, discarded most (quickly), and MM was much better than the alternatives.
By the way, organising the classical library entails some initial work, and extra work when ripping. Genres have to be set up, 'Filters and Views' accordingly, and when ripping 'albums' (pseudo-albums?) must be created for each individual 'work'. Once this is done, MM works well.