Also depends on your viewing angle.
If in the lounge, and you would most likely sit down to look into the tank, then a lower stand is better. You do not want to sit down and look up into those bright lights. But then again, the stand should be high enough to allow easy access to the equipment plus being able to take equipment in and out.
If the tank will be placed in an area where you would most likely stand next to the tank admiring the fishes and corals, then an higher stand would be better.
Depth of the tank depends on your arm length. Or if you can use a small stepladder. 800mm depth is the max although that is already too deep and your armpit will be wet trying to get something from the bottom. 600 to 750mm is better.