I've used FontExplorer X (Mac) for font management and testing since it came out - and now it's been bought by Monotype only to retire it. Thanks Monotype.
It's been perfect for testing fonts - uninstalling and reinstalling updated fonts without issue or difficulty. I particularly liked the drag and drop feature - and the speed at which adding and removing fonts was first and foremost. Not to mention the organisational features. Can anyone recommend an app that does the same? Fontbook just won't do - So far I have tried Fontbase, FontAgent, Rightfont - none compare. Suggestions please? Thank you!
The other major font management app is Extensis Connect Fonts, formerly Extensis Suitcase. It is now subscription-only, $108/year. https://www.extensis.com/connect/fonts
I do also use Font Book sometimes as a way to disable fonts that I wish to keep in the Fonts folder. I also use the collections feature in Font Book as another way to organize installed fonts. Collections show up in the system Font Panel in apps that use it. I have nearly 600 fonts installed, so this can be handy.
Manually managing fonts or using Font Book is fine for most. Font managers like Typeface just offer more benefits to your design process. Typeface app allows you to visually browse through your library and inspect font capabilities (OpenType features / variable axes / character support) in more detail. And it provides better organisational features (nested tags / inverted tags / multi tagging etc.).
For example: if you organise font files in Finder they can only be in one folder at a time. Whereas with tags (collections) you can add fonts to multiple tags, e.g. sans serif + fun + project/abc + favourite. There are much more possibilities and not everyone needs all these extra features, but they can considerably improve your workflow.