Not a good answer for anyone but a rank novice.
- Many of us have trained with multiple agencies over the years, so still which one.
- NOAA publishes tables/data that actually address the issue (ascent to altitude) and is highly respected, but is not a public training agency.
- DAN does not certify divers in the classic sense, but has a huge amount of experience with recreational divers and issues that should not be ignored
If I had to pick one agency to follow on this one it would be NOAA (not one I have trained with) because their data is published and vetted to some extent by the scientific community.