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Recommendations (for and against) are my personal opinion only and may be out of date.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 December 2021 I've updated most of 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.

(1 modules in list)
Module name or machine name
Any text in the notes
Name D8 Personally Tested Last Updated
Username policy (username_policy) 2020-06-24

d.o. page

This gives you a single box where you can enter tokens to form the default username.

It seems to work, but in D7 the patterns section ("Only use the below pattern elements") was empty. This is supposedly because there's a dependency on the 'profile' module, except profile doesn't exist in D7 (I tried profile2 instead but it made no difference) and profile2 doesn't exist in D8.

auto_username displays tokens OK and is more powerful / has more settings including customise at what point names are truncated, etc.