This is one of the most asked question. Like Andrey Lebrov puts it “The best render engine is the one that suits your needs the most. Find it and master it”.

Here are some helpful links that put you in the right path for finding best render engine for your needs:

Which 3D Render Engine Should I Use for VFX? By Ben Thomson
What Renderer Should I Use In Cinema 4D? By Chad Ashley
About Render Engines by Andrey Lebrov