My question falls more into the realms of subjectivity, but it should be possible to get a consensus on what most people would consider the most 'white'.
Standard incandescents have been around for ages, and I'm sure 99% of people wouldn't consider them nearly close.
A few years ago, I thought 6400k would be the closest to pure white. But I'm beginning to wonder if this hue is slightly veering towards blue after all. I remember reading a not-strictly-scientifically-controlled study done by someone who showed a range of hues to students and they said that temperatures around 4000-5000k were closest to what they perceived as true white.
I also came across this page, which also suggests 5000k is true white. Other sources will vary from anything between 4000 and maybe 7000 for their definition.
I bet you guys may know better though. Sources appreciated too.