I’m aware of the various assets stores and anyone who compares them has never used Unity’s. There’s plenty of places to get 3D models. There’s one place to get game ready, rigged, low poly, high quality models and assets.
Every store requires work on the devs part, Unity’s doesn’t (or extremely little).
I also don’t want to give Unity any more money so buying assets from them and porting them isn’t my idea of a good time.