Q. Does CMOS have a preference on “said” versus “stated” for attribution?
A. “Said” is more neutral than “stated” and would be the better choice in almost any context; “stated” is more definitive and sounds more formal. As a general principle, if any verb other than “said” is used, make sure it suits the context. For example, “wrote” could work for a written source, and “claimed” might be the right choice for something either written or said that hasn’t been verified (or that may be false). But try not to use a word like “sighed” that isn’t compatible with speech (see CMOS 12.41).