Hi,
it depends totally of what you intend to do with FC.
For me I have chosen to to install
- FCCircular Text
- FCInfo to calculating area, volume, mass moment of inertia etc.
- FC Spring Helix when I want to create springs
- Force Recompute
and there are a lot of Macros to choose from.
Be aware that you do not have to install the add-ons and macros yourself but via the Addon-Manager that can be accessed through the "Tools" bar on top of FC.