It depends on using the PC. I mean that someone uses PC only to play computer games or download illegal software. But other people use it to work in the office and to use office apllication.
So for gamers more useful is a desktop Pc, because it provides them better performance and more capacity on HDD. But for the official workers more useful and handy is a laptop, 'cause it is light, and smaller than desktop PC, and provides to workers good workstation to work in travel and wherever they are.