Synthetic group photos - where do i find great photorealistic artists?

Hello - I run a company that is building technology to generate photo realistic images using Unreal that import you and you friends in to fictional scenes. We need to find lots of incredible 3d artists to help build the photo realistic rigged assets for these scenes. Which are the best studios / individuals to work with if looking for best in class (we are generating still images only so no realtime rendering required)?
Thoughts appreciated