When writing charts, I prefer the delta symbol over the Maj7 notation. Then again I pefer the minus (-) over written "min" when writing chords of the same. Many jazz charts leave the player to intuit where to use the major seventh by watching the relationships of the ii and V chords. I generally feel that less reading means quicker hands.

While on the subject of non-jazz uses of Major sevenths, what about John Sebastian's "I had a Dream"?