At the time of writing, following "competitors" are known to me:
Plus, some inspiration comes from cvs, svn, svnkit, spring and other projects.
When creating this comparison table, I used this (in french) as the base.
| commons-cli | args4j | args-inject | |
| license | MIT | Apache | Apache |
| java version | 1.5 | 1.4 | 1.5 |
| declaration of options | runtime | annottations | both runtime and annottations |
| multi-value support | yes | yes | yes |
| embedded help | yes | yes | yes |
| custom value types | no | yes | yes |
| internationalization | yes | no | no |
| subcommands | no | no | yes |
| POSIX like options | yes | no | no |
| GNU like long options | yes | yes | yes |
| Java like properties | yes | yes | yes |
| automatic unmarshalling | no | yes | yes |
Note: should you find any mistakes here, please let me know