As an texture and lighting artist, rendering is extremely important to what I do. Not only does the render have to look beautiful and accurate but there is the problem of rendering time. The faster the render is the less I'm sitting around, twiddling my finger, waiting to see what my work looks like, and more and better iterations can be done. With so many renders out there, some proprietary, some I never heard of or use, there is a big question of which render engine to use. The ever so popular Renderman by Pixar, Arnold which I first learned about from watching Merlin, V-Ray, Maxwell Render, Mantra, Cinema 4D, Modo, Lightwave, Mental Ray, 3Delight, FinalRender, Octane, Clarisse iFX, and Lagoa. Particularly for vfx houses, such as ILM, they don't necessarily only always pick one and go with it but find an appropriate render engine depending on the cost and time production of the film that is being worked on.
On FXGuide, Mike Seymour writes an excellent article detailing each of the different rendering engines, how they are used, evolution, and strengths. Part one introduces the various issues that rendering engines have to meet while part two talks about each of the rendering engines. It is quite a long read, I haven't finished it myself yet so am slowly working through it.