The dead / (recovered + dead) is the worst-case assessment, since most of the people who have not technically recovered yet (but may not even have any symptoms anymore), won't die either.

The dead / (infected + dead) is the best-case assessment, since some of the people who have not recovered yet, will die.

A somewhat better metric would be dead / (infected X days ago) where X is the median time for the illness to fully develop.