Twitch & OBS plugins

Basic setup

Move: lets you animate all the things, from transitions to sources in a scene, to filters and effects. IMO, this is the GOAT of plugins, but is closely followed by...
Advanced Scene Switcher: Does so much more than switching scenes, giving you an entire macro system for automating your stream reacting to everything from scene switches to Twitch events.
Source Clone: Lets you clone any source (with almost no overhead) so that you can apply different filters/effects. Once you need it, you really need it. I dont think I have a single scene that doesn't have at least 1 or 2 source clones.
Downstream Keyer: Lets you specify something to go over the top of your final output. A great place to put follow/sub/etc.. animations and ensure they are shown regardless of the scene you are currently showing.
jrDockie: If you use a lot of docks, jrDockie lets you create sets of docks (much like scene collections) to turn off/on. So you can have one set of docks active for editing OBS, and another for when you're live.
QAU (Quick Access Utility): Gives you some very convenient docs, giving you quick access to sources that might be buried in your setup. Also provides a quick-search popup to find sources by name, type, file paths, URLs, and filters used. Its still in pre-release, but a v1.0 release will be on the OBS forums soon. Link goes to the github latest version download page. (DISCLOSURE-I wrote this plugin, and it is under active development)
Aitum Vertical: Lets you create a vertical scene/output that is rendered in parallel to your normal output. Makes creating tiktok and youtube vertical vids a piece of cake.
Aitum Multistream: Very new plugin that makes multi-streaming to multiple services a breeze.

Visual/FX/filter

ShaderFilter: Comes with a huge library of shaders to apply all sorts of crazy effects to your sources. Everything from rainbow effects, to drunk/distortion shaders, to scanlines. Also lets you build your own shaders if you learn HLSL (the shader language OBS uses). Super powerful.
Advanced Masks: Lets you mask sources in all sorts of powerful ways. You can mask a source using various shapes, gradients, and even using another source. Brings many of the powerful Matte/masking features from existing video editing software to OBS. You can also apply color correction masks for doing things like changing the saturation or brightness of areas of the source. (DISCLOSURE- This is one of the plugins I built)
Stroke, Glow, Shadow: Does exactly what it says- allows you to create strokes/borders, glows, and drop shadows around sources with alpha transparency. Allows for both inner and outer effects. (DISCLOSURE- This is also a plugin I built)
Gradient Source: Lets you create complex gradients in OBS. Something that really should be built-in, but for some reason isn't.
Composite Blur: Allows the blurring and pixelization of sources. Provides tools to do area, zoom, directional, and even tilt-shift blurring, using a few different blurring algorithms. Also gives the option to pixelate your source with different shapes including square pixels (think 8-bit games), hexagon pixels, triangles, and circles. (DISCLOSURE- This is also one of my plugins).
Scene as Transition: Lets you build stinger transitions but using a dynamic/active OBS scene rather than a pre-baked video.
Retro Effects: Send your stream back to the 80s or 90s. Gives a bunch of effect filters that do everything from simulating an old CRT TV, to the Matrix Rain effect, to Posterizing. Lots of fun visual effects you can apply to the sources in your stream. (DISCLOSURE- This is also one of my plugins).
Noise: Generate random dynamic fractal noise sources fields using several different algorithms. Can be used for backgrounds, with advanced masks to generate unique/evolving masks, or with the plugins Noise Displace filter, which applies the noise as a displacement mask for a source. Definitely a complicated filter, but you can get some amazing effects with it. (DISCLOSURE- This is also one of my plugins).

Source: https://www.reddit.com/r/Twitch/comments/1ezb7d1/what_are_some_plugins_yall_use_for_obs/