Many games support both keyboard/mouse and controller input. Many users (myself included) may wish to switch their input method mid-game, but what is the best way of handling this?

There are two potential solutions:

1. Have the two input methods combine and reach a consensus (e.g. pressing W on the keyboard while moving the left thumb stick to the left will cause the player to move forward and left)
2. Have only one input method work at any given time, but switch automatically depending on what the player most recently used.

Technically there is a third option, which is to have the user manually switch between the two input methods in a menu somewhere. I don't consider this a real option because the user experience would be terrible.

So, which solution do you think is better and why?