What's an ult that always brings value?

Simple question yes. But what ult gives you're team the upper hand in a fight or always at least get a kill in most instances. And if possible give an example for each role.

For me myself it's the following.

Tank: d.va it can greatly disoriented the enemy team.

Damage: Sombra is basically the most support damage ult, really gives the team the upper hand in any battle, can even cancel other ults.

Support: zen, can bring a tank back from imminent death and open up a push at the same time.