I started with XM 10k lamps, which i found to be to yellow. Once they were in need of replacement i bought some Ushio 14k's. The color on them was pretty good, but not as blue as i was hoping for. Once they got toward the end of their life cycle one of them actually started flickering really rapidly so i put one of the old XM's back in, to my surprise i could not tell the difference between the two. Needless to say I won't be purchasing those again. Currently I am running XM 20k's, they were really blue at first with kind of worried me, but after about 3 or 4 weeks they burned into a great color. I am very happy with my current lamps.
Eric at my LFS keeps telling me he wants me to try a set of Radium 20k's once I need new lamps. He will be changing all the lamps in the shop to those pretty soon so i will get a chance to check them out, they are supposed to be a little more intense then the XM's I think.
With lamps it seems to be a lot of trial and error based on personal opinion. For a long time i didn't want anything but a 10k lamp, now i wish i had changed over a long time ago. Keep in mind I am running a 175w single end setup. Color of the lamps should be the same but i can't say 100% that they will be.
