While I am also not a Rex fan, I agree with some people on the fact that it was a good predator, as are the rest of the carnivores in this list.

T-rex did a good job at hunting what it was built to kill: animals that were commonly not as large as it, usually well armoured and defensed. It developed a bone crushing bite to handle the thick armour and hide of Ceratopsians and Ankylosaurs and deal quick death to hadrosaurs.

Giganotosaurus and Carcharodontosaurus especially were apex sauropod hunters, built to tackle prey many times their size with razor sharp fangs and claws designed to try and hold on to the multi ton prey while they ripped chunks of flesh off before backing off and letting bloodless and infection finish them off.

Spinosaurus was a carnivore that likely preyed more on large fish of the time than land-prey, as do most crocodilians today. But it likely ate whatever it could catch with its claws and with its jaws. There is no true evidence to say whether it looked like the semi-quadraped, the biped, or the knuckle walker. I honestly prefer the knuckle Walker because that’s a nice image.

Allosaurus is built to handle both sauropods and stegosaurus, with it’s best to deal with armour and yet the speed and sharpness of tooth and claw to tackle big, dangerous game.

Lythranox is like a T-rex before there was T-rex, built for tackling the prey that would eventually become the iconic animals T-rex would battle.

Triceratops was designed to be the best a herbivore could get to be able to be a carnivore-killer with a socket behind its head as close to a circle has nature could get, allowing the head with a limb-breaking beaker and three massive horns, as well as a solid bone shield that protected the neck as best it could to move in almost all directions.
But Tyrannosaurus still hunted Triceratops.

What I’m saying is that While people can have beliefs that one carnivore is the best, we can never be sure which was truly the best, short of travelling back in time to grab all the dinosaurs and putting them up against one another.
Blame media for causing the Rex fandom with Jurassic Park, Cartoons, and Novels, when it’s the other types that made the world go around, not just a Head with legs that ate biological armoured tanks.