To the OP: You didn't mention what type of lights you have, but I'll assume SE bulbs since they are more common. I agree that the Radiums are the cat's meow, but you can't run them on all ballasts. If you are thinking about them, post what ballasts you have so you can be sure they'll fire.
The Phoenix bulbs make the corals happy, but are too white for me... when you've been used to seeing a 20KK bulb it's especially noticeable. Color is purely a matter of opinion, but unless you are only changing bulbs to get higher PAR output, I'd stay with 20KK bulbs if the color pleases you.
If you happen to be using DE bulbs, then your options are severly limited. I found the best option to be the Ushio 20KK. There are some (EVC, Helios) with a bluer look, but after talking to several retailers about the high "bad out of the box" rate with them, I decided to go with the Ushios.