I can't think of a single plausible situation in which git is not superior in every way to all the other version control systems.
I don't want to get into an emacs/vi style flamewar but other VCSs have their own advantages, and are better in some situations:
- I prefer SVNs handling of trees/subtrees. I can checkout and work on one small part of a large project.
- Fossil has ticketing and wiki out of the box. It is easier to set up a server and enables true distributed offline working.
- Mercurial is easier to use for the most frequent use cases.