For my DOSBox setup, I have mouse control set to a toggle. By default my left thumbstick acts as the standard joystick for DOSBox, but with a button press it's able to control mouse movement. I also have it set to change the two joystick buttons to left and right mouse clicks. This works well for the Atari ST and Amiga systems too, as several games need to be launched from an emulated desktop environment. Once the game is launched, I press the toggle button again and it reverts back to being a joystick. All that said, I still use a mouse and keyboard when I feel they're better suited. It all depends on the situation and the game.