Well you got one thing right, that is the face Natsu will give before Enel blasts him into oblivion.
Atlas flame natsu should win if enel can't use haki
Enel is logia, so even without using his haki, he will electrocute Natsu.
I can't think of anything in FT verse that can replace haki (unlike chakra in Naruto and nen in HxH).
As the OP said, no logia intangibility , i say natsu wins with atlas flame and lightning dragon mode since he can eat lightning