Nothing makes this list without me reviewing it personally and extensively. If you have an addon, asset, or training that you believe belongs on this list, please contact me for review.
One of my favorite and most long-standing texture resource websites. I prefer simple, straight image files where I don't need to juggle with .sbsar files.
Exceptional blend of artistry and technical insights. Some lack of structure, but valuable content. A rare glimpse into high-level environment art in Blender.
Poliigon is a long-standing staple in the 3D asset community. I trust their quality standards and have personally used their assets in many different productions.
I've used these so much in various productions! "Indoor Scapes", "Jungle Scapes", "Creeper Scapes". Each comes with a usefully categorized collection of vegetation for dressing different biomes.
Quickly add optimized animated 3D dust particle animations to your scene. To be fair, with it's interface, this is just as much an addon as it is an asset.
Very useful tool and accompaning free tutorial for creating convenient shape-key rigs for stylized facial animation. Tutorial → https://www.youtube.com/watch?v=1Is3oUvHwdM
Quickly automate and streamline the process of dropping objects into a scene with rigid body physics. Basically a better and faster interface for physics already within Blender.