4000K hands down if you have to pick one. Tint is stellar, beam is great and still feels at home as a Malkoff. If you are a big fan of warm, this current 3000K SST tint is sublime and seems to be higher output than the old XP-G2 80CRI, making the 3000K the no-brainer.
I'd get the 5700K if that higher output and thermal efficiency are important, IE you really want to maximize your lumens/ MA, might put mine on my 870. WML/ duty light kinda situations.
ETA: Link to SST vs XPG2 comparisons (5000K white balance, Galaxy S8) https://imgur.com/a/KHKOvFv
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