As always, The lighting you choose depends what you are going to keep.
I have two different 55's running, on with a Coralife 2 65 watt PC hood which is not enough light for most corals, but it's my zenia factory.
The other has a DIY hood with 3 110 46.5 in. VHO's run by 2 workhorse 7 ballasts. I've grown just about everything well in there.
So, decide what you want to grow first, then get the lighting.
Just in case it's not too late. I would trade my 55 for a 75 or 90.
I really hate the fact the tank is so narrow front to back.
good luck
Bill