At early levels, all of the tanks are really simple and mostly involve 3 buttons and occasionally a resource attack, so you can use whichever tank you want and you will probably get used to it.

Gunbreaker and Paladin are the most distracting tanks at level 80 (in my opinion), so you might find Warrior or Dark Knight easier. Dark Knight involves pressing a lot of abilities between your GCD so it can be distracting until you get used to them, while Warrior mostly uses the GCD so you have a lot of time to think between each button press.