Atmosphere js is the most widely used packages collection for Meteorjs framework. They are community build packages and are very useful and simple to use. You are not required to code thousands of lines from scratch , for getting the same functionality every time, instead could add a single line of command and you could have the package installed and the functionality working.
Atmoshphere js website: https://atmospherejs.com
Below are the packages i use for almost all projects.
meteor add materialize:materialize
meteor add johnantoni:meteor-normalize
meteor add accounts-password
meteor add kadira:flow-router
meteor add fortawesome:fontawesome
meteor add alanning:roles
What packages are you using, frequently?