4. Thor
When it comes to brute strength, it simply doesn't get more powerful than Thor. The God of Thunder is well-documented as one of the most powerful characters in Norse mythology and Marvel Comics, and that certainly extends to his portrayal in the Marvel Cinematic Universe.
Chris Hemsworth was the perfect casting for Thor, because he looks powerful. But the MCU's God of Thunder walks the walk too, because he's the most formidable and accomplished in terms of combat, having spent centuries battling all types of adversaries across the Nine Realms. He's fearsome enough without his weapon, but when throw Mjolnir and Stormbreaker into the mix, he's essentially unstoppable.
Another thing that gives Thor the edge over his fellow strong Avengers like the Hulk is his ability to harness the power of the lightning to attack his opponents with. When he shows up to battle like he did in Thor: Ragnarok or Avengers: Infinity War, his opponents haven't a hope of defeating him. Not. A. Hope.
I wish the MCU would be a little more consistent with the character (as he's depowered or played for laughs a bit too often) but the fact that he is capable of all of this highlights the endless potential with Thor's powers.