Keyboard and mouse, true support, as in mandated to have the options in the game menu for all games published, and its likely many pc gamers would jump ship. Hardware wise, the line is non existent, you just get so much more hardware way less money.
Of course there is the closed ecosystem but sony or ms, both are huge gaming ecosystems.
Its the keyboard and mouse. Game pads suuuuuck for so many games. Maybe side scrollers gamepad is best, but so many games the thought is, this would be better with.... Keyboard and mouse (or partial/ hand keyboard which are cool too)
I tolerate gamepads.