Swiss Army Knife of 3D Modeling Software
First, this is a very powerful and affordable 3D modeling software that has amazing compatibility with other software due to the thorough file extension list available for exporting and importing.
Second, I really appreciate the fact that McNeel does not force it's users to repurchase the software every year like other companies choose to do.
As if that wasn't enough to make Rhino appealing, you now have Grasshopper's visual-scripting capability built in.
Overall, it is hard to beat this software if you consider the cost to performance ratio.