WARNING: The following contains spoilers for Avengers: Infinity War! Proceed accordingly.
Avengers: Infinity War was the biggest film in the Marvel Cinematic Universe so far and the most jam-packed superhero film ever by a country mile. The sheer amount of characters is incredible and surprisingly, almost everyone gets a moment to shine. The battle with Thanos (Josh Brolin) had the highest of stakes, necessitating that all the heroes join the fight to try and save Earth, half the universe and each other. Nobody got to ride the bench in this film, but even though everyone got playing time, some Marvel characters really stepped up more than others.
Now let's be clear, the heroes lost, badly and completely, more so than I think most of us even anticipated going in. Half of them are dust by the time the credits roll and there is more than enough blame to go around. But even in a losing effort, there are still some characters who really stepped up and made a difference in the battle, and had the Avengers emerged victorious, each of these characters would have a legitimate case for MVP. Part of this is simply by virtue of the story being told, but I think it is noteworthy that not everyone you thought would be a big deal going in wound up being the all-star we might expect.
The pillars of the MCU, Tony Stark and Steve Rogers, fought a good fight, but they were not nearly as effective in the grand scheme as some of the MCU's other heroes, and heck, you could even argue that Hawkeye didn't do anything at all. So, with all that in mind here are the 5 Marvel characters who really stepped up during Infinity War.
The Hulk was completely useless in Infinity War. Suffering from performance issues, or a conflict with Bruce, the Avengers' ace in the hole refused to make a late-game save in the battle against Thanos. Bruce Banner however, really stepped up in the absence of his green friend. In addition to heralding the coming of Thanos (with an assist from Heimdall), Banner also made the call to Steve Rogers that ultimately saved Vision's life, albeit temporarily. That call was crucial, and delayed Thanos from getting the Mind Stone. If Thanos had gotten the Mind Stone sooner, it's possible that Dr. Strange's long-play may not even have been an option, or Captain Marvel might not have been called, thus eliminating that one chance at victory. Bruce also made a go of it in the Hulkbuster armor, refusing to let the team down even when he and his alter ego are going through some stuff.