Add-ons that would be great as restartless add-ons, since you only use them occasionally
Add-ons essential for your everyday privacy. You also need to use startpage dot com, and HTTPS Everywhere and Privacy Badger from EFF dot org. For special privacy, use Torbrowser instead.
Add-ons useful for shopping (ie. finding cheaper prices).
Themed personas I like to install on other people's computers.
A collection of lightly-coloured, clean (not-too-busy) personas I use (in rotation with the Personas Rotator add-on).
Extensions which are great but use too much CPU - if you have some über six-core machine then they might be worth using.
Recommended for your default search engine: The search engine addon at startpage dot com.
Add-ons which fix bugs, improve security, or add functionality that should be included in Firefox by default. See also my collections "privacy essentials", "functionality" and "newbie-suitable".
My favourite add-ons, purely for aesthetics. I also recommend my collections "bugfixes", "functionality" and "privacy essentials".
My favourite add-ons to extend Firefox's functionality, with minimal slowdown. I also recommend my collections "bugfixes", "privacy essentials", "pretty" and "newbie-suitable".
Only the most useful add-ons, recommended for everyone. I also recommend HTTPS Everywhere and Privacy Badger from EFF dot org. Also essential is my "bugfixes" collection.