Kovu,
you will get houdreds of opinions on this topic, Tunse, Vortechs, Korolias, depends on tank dementions, your pocket book, ect. My mentor has a 180g, 6'w,2'h,x2'd, runs 2Vortechs left to right on the ends on a randim controler, and some #2 Korolias back to front, lots of corales, I run in my 125g 4'x2'x2' two #2 Korolias left to right in the front of the tank, rock in back, then from back to front at the 2 lower back corners a Korolia #1, and the same at the top. I tried #3's on the side and blew my softies around too much, the #2's are at the top and are angeled down. It has worked fo me, if you have more hard corales, you may be able to do more flow, but with softies, less maybe better on them directly. IHTH's