Useful Drupal modules

Click on the module name for notes, comments, patches.
Recommendations (for and against) are my personal opinion only and may be out of date. Feel free to email with corrections/suggestions.

Why haven't you mentioned Drupal 9? As of February 2022 I've updated all the sites I look after to Drupal 9 (experience: mixed). I haven't decided how to label future version compatibility as D10 will be coming soon as well. The upgrade_status module is superb. You're bound to have issues with composer. Also watch out for a nasty session headers bug with redirect_after_login.

What about sites still running Drupal 7? In short I still recommend leaving them on Drupal 7. Your decision is really if you will gain anything from Drupal 8/9 and for many then answer will be no, and one of the main hassles - apart from converting each content type one at a time, and setting up a new theme, will be recreating all your views by hand, as views can't be automatically upgraded.

(1 modules in list)
Module name or machine name
Any text in the notes
Name D8 Personally Tested Last Updated
Role Delegation (role_delegation) 2018-11-20

d.o. page

Ordinarily, if you grant a user "Administer Users", they can do everything *except* change the roles (they don't even see the checkboxes).  You could give them 'Administer Permissions', but that also allows them to do other things.  

This module lets you set which roles they are allowed to enable for a user.  Administrators still see the roles checkboxes in the usual place (below 'status' on /user/123/edit), but everyone  gets a new 'Roles' tab.  

Works with D8 but not updated since April 2016.

Patches:

I'm not using any patches, but there are a couple RTBC-ed  the queue.