Hi @ArcticF0xx
As mentioned in passing by @Stephen, features and functionality outside the Discourse core are driven by the use case of each individual Discourse community.
For example, a tech forum based on coding or configuration may need some special plugins for BBCODE tags or additional custom MARKDOWN support. These plugins would be the “favorite, must have plugins” for a subgroup of Discourse forums, but would be “worthless” to other forums.
The same is true for other specialized plugins.
For example in the reply by @elijah, he lists discourse-spoiler-alert as a “must have”; but the Discourse forums I have worked with have no use for that plugin and no reason to install it.
As @HAWK, said:
As a general rule you will be covered by core plus any plugin labelled official
But for specialized Discourse use cases, and designs of your own vision and individual dreams, what is “the best of the best” for one type of forum is not necessary good for another use case.
If you really want relevant answers, you should describe exactly what is your forum, your goals and vision for that forum and for the “use case” of your forum.
But to ask a general question, across the universe of forums, as follows:
What are your favorite plugins for Discourse? What do you think are the must-haves?
… this is way too general, in my view, to get any useful information.
In closing, @AntiMetaman is correct, when he replies:
There are many and I think you shouldn’t just blindly install plugins. As said above, find your use case and then find the plugin.
All I am doing is echoing the wisdom of these replies. Do not install plugins for the sake of installing plugins. Do not install plugins them because others recommend them. Install plugins because they are required for you to fulfill the mission objective of your forum.