Three questions decide it, and they are worth asking in this order.
ONE: is it a DOCUMENT or an ANALYSIS? A document has a required appearance and a defined recipient — it is printed, emailed, or read by another system. An analysis is looked at on a screen by somebody who may want it sliced differently tomorrow. Document is BI Publisher; analysis is OTBI. This one question settles most requests on its own.
TWO: scheduled or ad hoc? Something that must run at 2am on the first of the month and land somewhere is a scheduled job, which is BI Publisher plus ESS. Something a person runs when they wonder about it is OTBI. Both tools can technically do both, and the tool that fits the rhythm is the one that survives.
THREE: does a business user need to change it later? This is the question that gets skipped and the one that decides who owns the artefact for the next five years. An OTBI analysis can be edited by a competent user; a BI Publisher data model cannot be edited by anybody but you. If the answer is yes and you build it in BI Publisher, you have just made yourself the permanent owner — see Lesson 5.
Where the three answers disagree, question three wins more often than people expect. A slightly less beautiful analysis the finance team can maintain themselves is worth more than a perfect document that requires a consultant every time a column is added.