How deep is you're tank? how many gallons? I think there are some corals (like mushrooms, or even low light zoos maybe) that you could grow with only 2-3 watts per gallon for an average height tank. If you want more choices for corals you want to bring that up to 5-6 watts per gallon and if you want the hardest stuff (like clams and SPS
) then you could need as much as 10 wpg
is more about the look you want or intensity you need than to say what is better, you can either choose your lgihting and get the proper corals for that or vise versa, decide what you want then get the best lighting for them in your tank...