The amazing Dropbox can sync just about everything, so why not your music? Well, if you use an iTunes-like app it will cause conflicts with your library files. Basically, you can't have a copy of iTunes running on your laptop when you open it up on your desktop. Fortunately, we've devised a way around this and have an entire guide explaining the process. It's not perfect and requires a little light scripting to help you avoid those conflicts, but it will work. If you don't use iTunes or another library file-creating music player, you can just dump everything in Dropbox without much concern. It can handle files and folders pretty much better than anything else.
The major downside to using Dropbox is the cost. If you can maintain a music collection under 100GB, you'll pay $100 year or $10 per month. While that's not a huge cost commitment, it's a lot to just sync your music. If you have an intensely gigantic collection, it'll cost you more. If you just want to sync music, you may prefer Google Drive. At half the cost, you can store a lot more for less. That said, Dropbox has a lot of awesome features in addition to sync and if you use it for that you might not want to switch. Either way, you can make it happen at a cost.