Bamibook
Bamibook lets you rate and create notes on other players, and notifies you when you get into a group with them. For example, you could maintain a blacklist of people you don't want to raid with. Moreover, if your friends or fellow guildies use the same addon, you'll be notified about their 'noted players' as well. Just type /rep when such a player joins your party/raid, and you'll get an overview of everyone's opinion on this person. There is an extra button on your "Friends" window to open Bamibook.
Bamibook has been moved over to wago.io, since CurseForge has blocked API access for WowUp, preventing WowUp users to update their CurseForge addons: https://www.reddit.com/r/wow/comments/urdcoc/curseforgeoverwolf_has_banned_wowup_completely/
This is why we can't have nice things.