When I grab an Xbox controller (or others with asymmetrical sticks), my left thumb naturally falls on the left stick, which is where it will be on a near-constant basis. But when I grab a PlayStation controller, my left thumb naturally falls on the D-pad. That's not what I'm going to be using most of the time (except maybe navigating in-game menus). As a result, my thumb is always having to crane down to the left stick, which causes my hands to cramp up. This is the main reason why I've always preferred Xbox controllers. They quite simply the most comfortable standard gamepad around. I know there's third-party PS gamepads with asymmetrical sticks, but most of those apparently have issues, and I wish Sony would offer official controllers with it as an option
Interestingly, the Wii U controllers has symmetrical sticks, but the opposite problem of PS controllers. My left thumb falls where it should, but my right thumb falls on right stick instead of the face buttons. Now, your right thumb is going to be moving back and forth between the buttons and right stick a lot, and it felt like I was in backwards land having to move my right thumb down instead of up to press the face buttons.