Best craft essence for Enkidu?

Holy night supper. Enkidu can generate a decent number of stars, so crit damage is good for him. His NP is one of the best things about him, so NP damage is also good and the starting NP gauge is always useful.

It depends on the situations, if you're using him as a DPS my top choice would be HNS/Imaginary Around ( HNS lean more into general set up/Crit set up and Imaginary Around for Quick set up ).
For Last Man Standing job or as a solo unit, use Guts CEs like Chaldea Life Saver.

Use it based on your playstyle and technically, the CEs will also follow your set up or tactics.