Where to spend Badass Tokens?

Borderlands 2 Krieg the Psycho
#1

I currently have 50 Badass Tokens and I have no idea where to spend them. There are a ton of possibilities but I was wandering if there are some that are “specific” to the class or worth invest in.
Thank you all.

#2

Health, melee, reload, fire rate…
Forget about shield bonuses, unless you have some other char.

#3

Thank you.