There are two usages of "most" which can be confused.
"This job is the most exciting (job) ever!"
This uses "most" in its superlative meaning: "much, more, most".
The other usage is the one you are thinking of:
"I find this job most exciting!"
which does indeed mean: "I find this job very exciting!"
How do you tell which one is being used?
If you see "most" without it being "the most" and without it being given in comparison with something else, it is most likely to mean "very".
Exercise for the student: at the end of the sentence above, which usage of "most" is being used? Be warned: it is subtle!
Finally, to answer your original question:
"Which aspects of the job do you most enjoy?"
uses "most" in its superlative meaning: "the most enjoyable aspects of the job."