What is the most cathartic movie?

I am just now watching the John Wick movies. Sounds like it matches your question.

"The pursuit of happiness" rings a bell, actors aside

First movie that comes to mind is Whiplash. Not sure if there's a tangible payoff at the end but you can see positive emotion in both protagonist and antagonist after the final drum solo. One of my favorite movies just for how visceral the setting is. A lot of discomfort even though you're not the one getting yelled at.

Shawshank Redemption

In my opinion, V for Vendetta. What Evie Hammond was put through was inexcusable, but I feel like it was worth it in the end.

The Big Short and Draft Day.

Dredd (2012) would be somewhere at the top of my list. I don't think there are too many movies nowadays that have such a classic "mission accomplished"-style ending.

Terry Gilliam's Brazil always does it for me. Depends heavily on which version you watch though, they're polarizing enough that you can play emotional Russian roulette with both versions.

Shawshank Redemption.

In a way, I think: Little Miss Sunshine.

A movie wherein everything, everything goes horribly wrong, and yet in the end you're left feeling absurdly good.