I have used XM 20K, Hamilton 14K, AquaMaxx 14K, Phoenix 14K, Radium 20K. Out of those I prefer the Radiums for a good combo of color and growth. I just got new ones today. I used the Hamilton 14K's on my first 75g, and I remember things growing really well under them. For for a balance of everything, I go Radiums though, a little more actinic pop in them.