Just type in LED in the search, this has been discussed a lot.
It's all about PAR numbers, and what you will stock. Most people who start with FOWLR eventually want corals of some sort down the road. In that case, the cheaper LEDs (ex. Marineland Double Bright) won't support corals; the LEDs that do are like $500 and they cover about 20sq/in.
I would go with (and I did) T5s. My light is the 48" Current Nova Extreme Pro and I love it. I did research for months since $400 is a good chunk of change and found T5s to be the best buy. Also, I didn't notice any dramatic spike in my electricity either. Probably the only things I won't be able to keep are certain clams and SPS corals. I know FOWLR is what you have... but I'm betting it's "for now".