Both types of light will give you ease in setting them up. The metal halides will run hotter than the t5's possibly causing a raise in water temperature. The metal halides give off glitter lines which many find very attractive and beneficial to corals.
I think it may be what you like better as far as aesthetics(eye appeal). I personally like the halides better and can basically keep any clam, sps etc. under my 250 and 400 watt halides!!!!
Just do a little reading of pros and cons, plus you have to make a decision regarding the kelvin(color of the bulbs) you want to represent your tank. _________ 125gal.w/Mag9.5 return(dual megaflow)>Mag7 pump Aqua Cev180skimmer.Wave2k Hamilton Reefstar(2)250watthqi(mh)pend.a Yellow, Naso Tang Red Lip Blenny Percula Clown Demoiselles Niger Trigger F. Wrasses Ceriantharia Orn.Shrimp and Stars Hermits Queen Conch asst. snails> Stars Zoos shrooms Montipora Brains Gorgonians Favia Turbinaria(large+small polyp) Acropora Xenia Tridacna (CroceaMaximaSquamosa) Leathers <35+75gal.reef tank as well> 
"IF THE PHONE DOESN'T RING...IT'S ME"  jb  |