Both are different and each has advantages and disadvantages.
The integration of Corel Font Manager in CorelDRAW where the application by default constantly monitored the font folders and allowed access to fonts in the application even if they were not installed was in my opinion a mistake. Corel listened to some designer some where and made a silly designer mistake. I configure CorelDRAW and CFM to operate like a standard font manager and prefer CFM over Font Navigator due to modern font support.
btw this is one of the most popular request, and one of the main features of the new font manager, since it allows to use fonts without the need to install each one.
There're several advantadges for FontManager, for example it allows to manage over a million fonts, far more than FontNavigator and some others.
So which do you vote for? CFM?
Yes, Max, Font Manager is far better than FontNavigator.
Anyway, for some users the old FontNavigator could be more simple and easy to use. But today is just part of the history..