My typical advice for larger tanks is twofold. First, even though others mean well, look to people who actually solved this problem instead of people with smaller tanks that assume that what they do will scale - as you know, it does not. Second, reflectors are your friend to cover large areas.
In the end, no matter what you choose, you will be using the same electricity, so just think about ongoing costs (bulbs vs 5 year replacement of most LED panels (maybe less with cheaper units)) and what you like to use and look at. You might start with less, but you will likely end with the same. Also, you can use different wattage lights over rockwork and less over open areas to be more efficient. A 400w MH over an area where you want lots of acropora is not too much more energy and you do not have to use that much everywhere else. I was planning a 16x4x4 tank with three main islands and about a 4' open space between two of them and I was only going to put MH over the rock islands. Not being uniform can save a lot of energy and stuff.
For an example, on a large tank, Dr. Joshi used 10x Radion xr30s to replace 3x MH for coverage and output. He has written about it a lot. No power savings to do the same thing... but he did it for other reasons.
It is no secret that I use MH for my larger tanks. If somebody made me use LED, it would likely be Photon V2 since they are powerful and cover larger areas.
