horse3d

You can't say any of these is "more correct" from looking at the renders. Those hard shadows stem from a difference in light size, which is almost certainly a problem with the scene parameters being treated differently. The light size may have been "lost in translation", turned to 0, creating a perfectly sharp shadow.

In theory, for "unbiased path tracers", the results of all three should be the same, at infinite samples. Rendering for a finite amount of time, lower noise suggests the renderer is more efficient.

In practice, every renderer has different features and settings, so the actual scenes will only be approximately the same.

Few people use Blender professionally, but those that do almost certainly will use Cycles. It's very capable now, quite similar to Arnold, but not as fast.

Hello there, "Math Nerd". While you're comparing Appleseeds and Orangepeels, I'd just like to point out that indeed we do need all this material/shader "garbage".

If you're disappointed with the state of the art, maybe you don't really understand the state nor the art?