Honestly I'd have to go with Tyrannosaurus
Spinosaurus is a lanky motherfucker built for a piscivore lifestyle, you can see it in the shape and structure of the snout, claws, arms and teeth. And that spine was a huge liability in combat. It hindered movement and any damage to it would damage the spinal cord which would likely be fatal.
Giga is much better suited for combat, but doesn't have the muscle mass or strength Tyrannosaurus has. It was built more for running fast while hunting, which doesn't help in a fight. The fact that Tyrannosaurus' bite is a one hit kill almost anywhere it lands is a huge factor
And before anyone says anything about arms, look at the pic I am replying to and pretty much any kind of Giga or Spino skeleton and try to tell me that they will be able to reach up to the facial area where most of the fighting is taking place
Overall Tyrannosaurus >> Giga >>>>>>> Spino