Not counting Thanos.
MVP's? Stark's team of him, Strange and Peter.
Came up short? Cap 100%, felt like he was only in this movie cuz of contract barely did anything noteworthy and I barely even felt his presence, when he was off screen I did not ever think about him, such a shame for someone dubbed the First Avenger.
I agree with OP, RE: Starlord. Written badly I mean that moment on Titan was so OoC.