Obviously you're not thinking about costs, so the comparison is apples to oranges. Personal choice.
Do you like the look of T5 or halide? Corals will thrive under either.
(If you stack up the costs, then it's Hydras by a mile. I would also think 4 hydras would be more compraable to the T5 fixture....long term costs still stack up in favor of the Hydra though.)