Which truck should I choose???

Go with the Pete.

I've put 114k on this 2019 international and I wish I never gave up my Mack. The X15 is the efficiency model that has been further neutered by company programming. It will drop gears on any incline and take 5 miles to get to cruising speed. The transmission computer is norlt programmed for tanker work and you will constantly be dealing with surge. It will also randomly decide to wait several seconds between pressing the go-pedal and adding fuel to the motor, usually when you're trying to pull out in traffic.
It rides smoother than the Mack but Rougher than the Petes. The headlights are worthless on any rural highway.
Mine has been in the shop twice. Once because of an issue with the rears, and once cuz the belt tensioner failed at 40k miles.
The Pete will be much more comfortable if you intend to stay out more than a few days. Better visibility and the interior feels much higher in quality. The transmission is more responsive, as far as autos go. I haven't noticed a significant difference in turning radius.
Our terminal is getting rid of all our Petes for alleged mechanical issues, but none of the drivers I've talked to have confirmed this. I say take the Pete and hold onto it as long as you can.

 

I say Pete. I drive tanker and an International. I have no room in my truck. Our company went with these regional style internationals and it's a bed that hits the back of the seats and 2 overhead bins. Hate it. My coworkers Pete's are so roomy and quiet. One is driving one with 450k miles and runs like a dream. I told her hold on as long as possible because when they retire it she'll likely get an International.

 

Say Hi to my old friend Serge.

 

Pick the Pete. Intl has too few miles. Stay way from it.