It depends what you want to do with it... assuming growing plants, what do you have your eyes on?
I would probably say LED with optics providing a lower disbursement angle would be your best bet.
for comparison, I have a Finnex Ray2, maybe 20" above substrate, I would say it's low light, maybe low-medium. so 2 of them might work, but I would look toward something with better optics, maybe custom.
The footprint of the tank may be a consideration, for something squarish, a kessil might be a good option.