would it be better for a 75 gallon tank for all types of corals to use a single high quality customizable light, or two black box lights to fit the color requirements? Any specific brands I should look at or avoid? Thank you!
I would say it depends on if you have a hood, open top, or have an actual wooden top that hides your lighting equipment.
If you don’t mind the look of more lights, I would go with multiple lighting fixtures to make sure you cover all of the spectrums for enough time (you can even have lights on various schedules so it's not super bright when they first turn on, and not jet black when they all turn off). Otherwise, you can get one lighting fixture but make sure it covers corals primarily if you have any, since lighting for the fish is a secondary aspect (only benefits the owner, outside of letting the fish have a day/night cycle).