I have ran all 3 on my tank but i voted 20k because out of all of them, with my ballasts they have given me the best results. My tank is very shallow so im not looking for light penetration.
I run 12K , Would like to use Radium , I have DE 250's.
3 250w 12k DE
4 24in VHO URI
2 6ft VHO URI
I run T5s on my frag tanks with nice growth and color