From personal experience, any of the higher temps that have the perceptable blue/purple tint seem to provide less visibility than stock incandensent bulbs, but the HID's I bought from Roe Racing (before they quit selling them) don't have any blue/purple tint and are definitely better than stock, so I would guess the lower temps would be the best. I don't know the exact temp of my Roe units, but the ballast says Phillips.
The higher temps seem to just be for the poser/ricer crowd.
