We should also consider tint differences - based on the available data, 4000K seems to be the least rosy of the CCTs being considered:
519A 4000k domed, 3779k, 0.0009
519A 4000k dedomed, 3027k, –0.0027
519A 5000k domed, 4696k, –0.0008
519A 5000k dedomed, 3654k, –0.0057
519A 5700k domed, 5281k, –0.0024
519A 5700k dedomed, 3969k, –0.0053
Source is this thread.
There may be a calibration issue with the CCT values, but looking at the DUV values, 4000K is the only one with a positive DUV (greenish).
My take is that if Sofirn can order them, most people could prefer the Hopthink/HSXLED (also known as FFL or NTG35). They offer slightly higher output than domed 519A and a better tint than dedomed 519A. Plus, they’re significantly cheaper.
If we have to choose from 519A, I’d consider 5700K (highest output, closest to daylight for work use with UV, and it can always be dedomed later to get a rosy ~4000K).
If it ends up being 4000K, I’ll probably have to dedome it anyway because of the tint, which would push it down to a very warm ~3000K. That’s not necessarily bad, but for UV-related stuff, like mineral hounding, the color rendering isn’t very natural anymore.
I think we should put more thought into the LED choice than just “it looks like most people want 4000K.” I’d rather see a more informed discussion where experienced opinions carry more weight than a simple vote count (and I don’t consider myself an experienced user).
Let’s listen to this guy, he knows a thing or two 
about LEDs: