You can grow corals beautifully with any of the fixtures listed so I think it's going to depend on what your expectations are and what is most important to you. If you want the completely polished and beautiful interfaces I think the Radion would be ideal, and the Hydra close behind. The Rapid LED Corona may be more energy efficient than the RB or SB lights since the rapid fixture is using CREE leds and I'm not sure what the SB and RB are using, but the hydra and Radion will also have CREE.
I would like to revive this thread. I'm trying to light a 75g as well and I was totally sold on t5s but now I'm really considering sbreef lights... what do you all think? My biggest issue with LEDs is not knowing what settings to run them at... t5s are just really plug and play...