Tablet / iPad
A bigger screen means fewer mis-taps and a readable minimap.
What it changes
Wider spacing between skill buttons means fewer accidental neighbour taps. The real gains are easier aiming on targeted skills, and a minimap large enough that you see it without deliberately looking. How often you check the map maps directly onto winning, so this is a genuine advantage. The cost is weight — holding a tablet in both hands for long sessions tires your arms, and it is not portable in the same way.
What to look at
Bigger is not automatically better — what matters is whether your thumbs still reach toward the middle of the screen. If they do not, you end up shifting your grip, which costs time. Weight is judged better in the hand than on a spec sheet. In-game UI layout is saved per device, so if you switch between phone and tablet, set up both. Adjusting your UI layout and button sizes often does more than changing device. If you mostly play out and about, stay on a phone.