With that large of a tank avoid LED
to get LEDS that will give you proper lighting it will cost you ALOT of money. Go with MH
or t5ho Lighting these are both great options, The T5HO will run cooler, Cost you less in electricity. I would go with the 180 because the lighting will be more efficient and there arnt many fish that are reef safe that require that large of a tank. However bigger is normaly better so your call if it was me Id go the 210 because id figure if I didnt go 210 id kick myself later down the road. the price difference between the 2 may be drastic im not sure however. Good luck taking it slow, thats what I say every time I start a tank then I some how obtain everything in a couple weeks when I planned on allowing it to take a couple months lol. LED imo
just isnt there yet in the technology to be great with reefs it can be done but it will cost you and most the time its DIY project.