This question can be answered very simply by looking at your needs for a computer. If you need a computer that can be carried around, with a built-in screen, then a MacBook is for you. Think students and mobile professionals. For others, a desktop is the way to go. It’ll stay locked in one place, but you can easily pair it with a bigger screen and more comfortable peripherals.
Of course, a MacBook can also be plugged into a large monitor, making them more flexible. A desktop will cost you less for more power, however, which is also worth thinking about. For family computers, something like an iMac is perfect, with a great price and good features.