From the TeXbook:
The
correct way to refer to \TeX\ in a computer file, or when using some other
medium that doesn't allow lowering of the `E', is to type `^|TeX|'. Then
there will be no confusion with similar names, and people will be
primed to pronounce everything properly.
(that is copied from the TeXbook's sources, the result wouldn't contain the ^| and | around TeX but print TeX in a typewriter font)
Since the "La" of LaTeX stands for Lamport, it is reasonable to use LaTeX based on the directive given by DEK.
To address the question when lowering the E is a viable option, it really depends on where you use it. In a block of text the strange formatting can be distracting and hinder fluid reading. Because of that the team behind learnlatex.org decided to not format it that way in the text but just use LaTeX. On the other hand, in logos or outside of real text, I'd use \LaTeX if possible. E.g., in my own CV I'd use \LaTeX in the skills section.