Get the EYE Hortilux Super HPS or dual spectrum if you have the cash.
As for ballast choice, in my experience all digitals have the same performance, so get whatevers cheapest. Also checkout Quantum and Solistek, I think they are cheaper than Phantoms and Lumateks..and they work absolutely great.
The one feature you'll be seeing is Dimmability. This is great for transplanting plants from a veg room to flower room, you want to dim the lights at transplant, because HPS lights are much brighter than MH. So if your light fixture is close to your plants and you switch to a HPS lamp, your plants could get lumen shock..which will stunt your growth for a week or two.
