Well, everyone knows that the best software is "John's Model Maker", which I made myself and I'm currently selling for $15,000. Please go to my site and buy it. :)
Just kidding!
Seriously, though, I wrote about this very issue in a blog... scroll down to point #3:
https://jhoagland.wordpress.com/2014/01/31/some-common-digital-model-myths-debunked/
First, how do you even define "best"? I don't mean to put down your question, but it's like asking what's the best flavor of ice cream. (It's "chocolate chunk cookie dough", but that's not important. ;) )
When you ask what's the best software program, do you want a modelling program that’s easy to use, but may not create efficient models? Or do you want a program that requires a little more learning, but makes optimized models? Or do want a modeller with integrated animation or character design tools?
How will you be using the software: will you be sculpting organic models or making hard-edged spaceships?
Or is software considered the "best" because it's free?
My suggestion is download a trial version of every software, use it until the trial period ends, and see how you like it. Maybe your "best" software isn't the same as mine. ;)