What MDX functions do you most commonly use?

This is a great question because you only know this answer by experience. If you ask me this question, the answer practically rushes out of me. “CrossJoin, Descendants, and NonEmpty, in addition to Sum, Count, and Aggregate. My personal favorite is CrossJoin because it allows me identify non-contiguous slices of the cube and aggregate even though those cube cells don’t roll up to a natural ancestor.” Indeed, CrossJoin has easily been my bread and butter.