Asciidoc is a lightweight markup language, Sphinx is a document processor. I imagine what you're primarily asking is "how does Asciidoc compare to ReStructuredT

Asciidoc is a lightweight markup language, Sphinx is a document processor. I imagine what you're primarily asking is "how does Asciidoc compare to ReStructuredText?". ReStructuredText has a ton of functionality, but it slips behind Asciidoc in a few areas. On paper, we passed by RsT because leadership didn't like the Python-forward tooling and high setup workload . . but we had other reasons on the publications side of things: less XML interoperability, worse print options, worse tables, weirder directives, syntax inconsistencies, no established spec or working group (at the time). Being built on DocBook is a great insurance policy for Asciidoc, as DocBook has been around approximately forever and opens lots of doors to other XML specifications via XSL or something more sane.