Which freeware is best for rendering??

No one... If you want have a good render you need pay.

Why don't you use Solidworks' 360 render engine? I rendered the image attached entirely in Solidworks. ...Including any illumination and translucency.

Answered with a tutorial: https://grabcad.com/tutorials/which-freeware-is-best-for-rendering

try keyshot 4.0

Try this
http://home.lagoa.com/

Try these 25 different programs,

http://www.hongkiat.com/blog/25-free-3d-modelling-applications-you-should-not-miss/

Look into Blender; an open source 3D creation platform:
http://www.blender.org/