My Mini Factory is primarily where I get mine (if you want a list of users I primarily buy mine)
Cults3D is another place but they're a lot more hit and miss on quality IMO
The best models are purchased models (in general) though MZ4250 on Printables models are free and also pretty high quality.
Personally I won't pirate models of people in the 3D printing mini community as I want to support the creators in that space as they're not giant megacorps.