To tell you the truth, it's mostly for the appearance and that's just your personal preference.
Actinic can better penetrate water so it's slightly better at geting to the bottom of the tank. It's also "photosynthetically yummy", to use a phrase from Eric Borneman, but most research has proven that coral can modify their pigmentation to take best advantage of any available visible light.
There are small differences in the amount of useable light (PAR) from the different bulbs, but I do not believe them to be significant differences. The best for the corals would probably be all AquaSuns but it would not be that aesthetically pleasing, at least not to me.
Me? I use half SuperActinic and half AquaSun. I like the SuperActinics a lot and the AquaSun bulbs have superior output for about two years so I save money using them.