Metal Halides will be the most versatile lighting you can use on any tank, but you have to be prepared to deal with the increased heat, evaporation and humidity. If you plan correctly and deal with those issues, MH are the way to go.
I myself run T5's and will on my next tank. My apartment just gets way too hot in the summer running MH.
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32"x32"x20" Cube-ish tank
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