If you like a crisp white look with no visually apparent blue, then Phoenix 14k on a magnetic ballast works well.
Or, a Geisemann 13k/14k bulb (one of my favorites for a natural non-Halloween look).
Personally I use the Radium 250w SE on a Galaxy ballast. Galaxy makes an awesome ballast (electronic), but the obvious blue of the Radium gets on my nerves a bit although my corals are doing well with it. I think I'd like the color better if I used a magnetic ballast (less blue, more white).
Nothing beats personal experience $$$$