I don't have now nor have I ever had those problems with iTunes, so that's not the type of thing I'm referring to when I say there are some sucky bits.

I'd say that your issue is not an inherent problem with the iTunes design nor implementation however, otherwise there would be thousands and thousands of complaints about the same issue. There has likely been a solvable problem there and it's something that Apple's support should have been able to work with you to fix. At least you'd have been entitled to have them try.

I don't think I've tried all the music software either, but I have tried SongBird, Media Monkey, that JR program, MusicMatch, software from Creative which I can't remember the name for and a few others that I also can't remember the name of. This related only to apps that can actually manage a collection, so I don't include the older versions of WinAmp that I've used and I have no idea how it's progressed over the years since I stopped using it - I don't really listen to audio on my computer, so that part's not really a top feature for me (though iTunes handles playback quite well anyway).