I know my way around Musescore. But sometimes handwriting still feels the most quick and distraction-free way to go for certain studies. There are many generic note taking apps on the iPad which allows loading a staff paper background. However, I did find one app specifically designed for music writing. It is simple, beautiful, buggy, and still under active development by a guy who answers emails. One feature that stands out is the ability to customize the spacing of the staff. And no, it won't export to MusicXML or any that sort of thing.
Do you write music by hand? What do you use?
