With console FPS you have a baseline graphic capability and usualy above average multiplayer.
With PC's though depending on your computer's capabilities it will either have horrible graphics or amazing graphics, multiplayer is about the same sometimes better, and with the PC there is usualy more custom content.
So console games are good for people who don't want to/can't upgrade their computers but still want to experience the game. And the PC versions are for people who want the fullest of the experience.