Superman
does possess more physical strength than The Hulk though.
All he'd have to do is fly over to him and snap his neck. Hulk can't do that to Superman because Superman's neck can't be snapped.
The Hulk is a raging behemoth. Superman is an invincible man. You can't kill something that is invincible. THAT IS THE DEFINITION OF INVINCIBLE.
Unless Hulk is made of kryptonite, he's not winning any fights against Supes. End of story.
Hulk doesn't need to kill Superman, he just needs to kick the **** out of him if he makes a mistake. All I'm suggesting is making a more entertaining fight. Comic book history is full of senseless power upgrades for the sake of trying to grab attention, but after awhile some of these guys stop resonating. A Worldbreaker Hulk or a planet-moving Superman aren't all that appealing to me. I think it's better to get back to what made these characters iconic to begin with. What do they represent?
Hulk: Pure uncontrolled and unfocused rage, taken from the mold of Jekyll, Hyde, Frankenstein and Freud. The fact that he was meant to be a heroic vision of that rage means he generally does more good than harm, but nothing is safe if it gets him angry. Anger does in fact make all of us stronger, we know this from experience. There's no better representation of that in comics today which is why I place him so high.
Superman: Truth, justice and the American way. He's got the innate powers of a medical center, an army, a construction crew and a deep respect for law and order. He really does represent the country as much as any other superhero out there, including Captain America.
Supes is in many ways the Hulk's opposite: he's an intact personality, he's restrained, he's intelligent and judicious. This is also what helps make him first among all superheros and why he'd win against the Hulk, but he'd have to win his way. He can't outdo the Hulk in brutal physicality. No amount of BS stats on strength really matter because it's more about what these guys represent which is also why they ought to resonate.
But by all means continue to further ruin Superman by making him ridiculously powerful (200 quintillion tons?
), all that does is make him boring.