No one exercise really. Ive always done a large variety of exercises and high volume. Lately my delts have come up alot just from incline and flat benching (many sets to failure). I was also hitting shoulders seperately as well. Often I just use side laterals with dumbbells for my seperate shoulder work. I get enough presses from the benching. When I was doing shoulder presses Id use dumbbells. I like those alot. I also like the cybex plate loaded shoulder press. Was doing that some months ago as well.