I actually think it's somewhat of a mistake to look at it as an either or on the basis of one being better than the other.
If you look at the results people have gotten with LEDs and T5s, it's clear that either will do just fine.
There are many other factors besides light that go into success with corals - that is why you see a dramatic differences between different users' tanks.
If you were already using T5 and having success with it I would not automatically switch. If you were fine with the budget required to maintain T5s then there really isn't a very big argument toward switching.
However, LEDs are much more efficient and power use and require replacement only every 5 to 10 years, perhaps with some power supplies replaced along the way.
How you like to play your cards, however, LED fixtures run the run the gamut of price points and feature sets. Many of the more popular commercial fixtures are so expensive you almost don't save any money in switching. YMMV, but that is not acceptable for this particular reefer. Thankfully, there are commercial as well as DIY options at the middle and lower end of the price range well.
Give us an idea of your budget and preferences and we can probably make a good recommendation.
