Well a good general rule of thumb is 5 watts of light to every gallon of water.
IMO I prefer
PC. They are not as expensive as
MH, and I have been told they last longer.
MH also gives off a large amount of heat so you will have to keep an eye on that.
PC does give off heat but not in the amount that you will have to worry.
All corals are diffent so you will have to research to see the preferred lighting for them.
But Bubble coral, Green star Polyp coral, Mushroom coral, some brain coral are just an example of what is good with
PC lighting. There are a lot more corals that this lighting is ecceptable for.
But being a 30 gallon tank I strongly recommend the Power Compact,
IMO.
Hope this helps.