Preferably in a Word document or PDF, but it doesn't matter too much; I can usually adjust it if necessary. For administrative purposes, it's often useful to keep a script on file with a recording, rather than just as text in an email.
Sometimes it's nice to select and copy the text to something like Word, for example, to move things around or insert a blank line. A document in which I can't select anything can be a limitation in these cases.