I think Hayward is loads better, he is better at creating his own shot than Jeff, younger than Jeff, has better stats in every area except shooting percentage.
Jeff is pretty much a player that scores off other people's set ups, where Hayward often initiates the offense in Utah. This team needs shot creation and Hayward is better at creating his own shot.
I would probably give up Green, Bogans and a heavily protected future first for him.