When comparing CDM vs Entrance, the Slant community recommends CDM for most people. In the question“What is the best Linux Display Manager?” CDM is ranked 3rd while Entrance is ranked 10th.
Ranked in these QuestionsQuestion Ranking
Pro Has almost no dependencies
Pro Supports virtually any DE/WM
Pro Very lightweight
takes up near no system recources.
Pro Does not need Systemd
So it can be used on other unix-like operating systems besides linux without the need for linux bindings.
Pro A Sandbox
Entrance is probably the most configurable and themeable display manager available.
Con Bad availability in distros
There is no CDM in distros repositories (only in AUR on arch)
However you always can compile it from source.
Con Curses-like interface
Very simple and minimalistic graphical interface.