Briefly, led are mst efficient, cheap tp run, not completely proven to thevsatisfaction of some people.
There are no bulb changes, no color drift, dimmable, more expensive start up costs unless DIY is your thing. Spectrum based on the leds used in the fixture. Great shimmer efct
Metal halde are the goto lighting for coral keeping, most complete spectrum of ligt. Run hot,may need a chiller, bulbs shiftband need to be changed emvery 6months to a year, energy sucking, good shimmer effect.
pC just stay away from.
T5 are nice as well, more effecient than MH but not near the light output. So many bulbs are needed to keep the light loving corals, no shimmer effct, bulb changes same as MH, used for actinic supplementation wit led and MH setups.
Honestly googe reef lightin, get a casevof beerband spend the next 10 hours reading.
Myself, i went with the diy leds, 800 bucks to light my 5ft tank, no bulb changes, and completely customizable in the future if new leds come out. These lughts will last forever with onlya slight loss of intensity a decade later.
See my build tread in te diy section of forum.