what is the toughest and best form of marital arts?

It's a matter of some people's opinions and perspective. I asked my first Karate' instructor this same question over 35 yrs. ago. He said " There is always a higher mountain".

Russian systema one mind any weapon.... it is a whole new Frontline system. I hate to say this but there is a reason the Spetsnaz are some of the world's toughest. And this is coming from a United States Marine who trained with Special Operations

Marine boot camp!

The deadliest would be...

Krav Maga – Israeli self-defense and fighting system.
Combat Sambo – Russian martial art and combat sport.

The toughest for competitive fighting would be MMA.

The art of fighting without fighting 🤔

Virtual Box Configuration style