If it’s a fight, then Spinosaurus. Recent evidence suggests that Spinosaurus was a pretty active land hunter and could take down relatively large prey. And there is evidence that Spinosaurus did compete and fight with other predators like Carcharodontosaurus.
Spinosaurus is also heavier, Parasaurolophus could get between 4-5 tonnes, which is an extreme low end for Spinosaurus specimens, and those are usually juveniles, while adult ones can get upwards of 7-9 tonnes with current evidence (tho some suggest it can get bigger)
Spinosaurus has a-lot of advantages here if it truly came down to a fight.