I can understand how the idea got started that 3000K isn't "good" for veg,... but it's a totally wrong idea. 3000K full spectrum LED works fantastically for veg.
Higher K emitters have slightly better efficiency. 3500K provides a small boost over 3000K and provides a more ideal ratio over 3000K in the red/blue department but when it comes to growing the effect will be slight to unnoticeable.
Still, we have choices. No reason not to use 3500K unless the chamber is dedicated veg in which case 4000K will provide a slight efficiency boost.
It's been shown that stem and leaf characteristics are affected by red/blue ratio, but again the ranges we're working with, effect is slight.
Bottom line is that 3500K follows the Mcree curve most closely and provides "enough" blue, the only better choice would be higher CRI, but at the expense of photons it's not worth it.
