I am a SUPERMAN fan, so would tend to see this more objective than either Thor/Hulk fanbase does!
Yes, I do believe you are more objective. I am a Hulk fan and felt this was a normal back and forth battle like they almost always have. I do not have any qualms in saying that yes, Thor was winning when the Grandmaster interfered. But winning does not equal having won. The Hulk took damage like no one else in the film and he kept on going. In the "Incredible Hulk" film, he was losing the whole time against the Abomination, and then he won.
Also, this wasn't the true Planet Hulk storyline. After being on Skaar for a long time, Hulk became stronger and stronger. In "Thor: Ragnarok," he was not shown as getting stronger as he was getting angrier. The MCU does not follow the comic book universe. Except, of course, with your Superman. He was ass-kicking in "Justice League."