Will whoopsie work without apport? If not, then it should have apport in "Depends". (It is not clear to me exactly what whoopsie does or how it works; there is no man page, and no relevant documentation in /usr/share/doc/whoopsie)
If either package benefits greatly from having the other installed, but it is not an absolute dependency, then the other package should be in "Recommends". That way the other package will be installed by default, but can be uninstalled if you want.
Will whoopsie work without apport? If not, then it should have apport in "Depends". (It is not clear to me exactly what whoopsie does or how it works; there is no man page, and no relevant documentation in /usr/share/ doc/whoopsie)
If either package benefits greatly from having the other installed, but it is not an absolute dependency, then the other package should be in "Recommends". That way the other package will be installed by default, but can be uninstalled if you want.