lighting depend on your tanks dimensions most importantly height in which it has to travel through water. also theres the asthetics part of it , you wont get the shimmer from t5 as you will from halides.alot of led fixtures do have a shimmer though. what you plan to have in your tank is also a big factor if you want a full blown sps reef youll need to research a bit more than you would for a lps/softie tank.
heating issues are def a factor with halides but there are ways around them while led have super long bulb life while some question there growth rate....
at the end of the day ask yourself what you dont want to deal with and what you want to have then see if it can be fit into your budget..
good luck