The best textures and Blender Materials you can get are from Quixel Megascan. Quixel has special equipment and is using a consistent workflow. Not only does it mean that the textures are of high quality, but it also means that you don’t have to adjust different materials. If you collect textures online from several places, the relation between the image textures got lost because everyone is using different equipment and has another workflow.
To get the best Blender Materials from Quixel Megascan you use Quixel Bridge. Quixel Bridge is always free. The textures are not free unless you sign up with Epic. But then you can only use the textures in a render (on your model) or in a game.
But if you use a personal license for a few months, you will get enough textures for the rest of your life you can use. And you can use these textures to bake on your models and sell your models, which is confirmed by Quixel. They just don’t want you to re-sell the textures (or give them away for free).
I asked Quixel if I could bake their textures on my models, and sell the models. This was their answer;
It looks like you’re using a Personal plan. Under this plan, you’re absolutely allowed to bake textures into models and sell them on any marketplaces you’d prefer - just make sure that the raw assets aren’t accessible. In situations where you’d be applying foliage atlases to trees, however, that wouldn’t work - the users would have access to the raw scanned data and thus it would run afoul of our Terms of Use.
In the tutorial I show also Anti-tile by thatimster, Botaniq, and other great add-ons for vegetation. And not to forget the Quixel Helper addon.