My feeling is that a desktop will typically be more of a workhorse plus the parts are more easily replaceable than on a laptop. But, let’s not just end the debate there. There’s more to it. There’s cost, size, speed, and well, looks of course.
Why go with a laptop? The size is a big plus, no opposite pun intended. You can have it home, in the office, travel with it and well, it’s your baby and you can carry it. Okay, let’s not get carried away here. But, in terms of carrying, you don’t need an iPad or worry about remoting into your computer somewhere if you just plain have one in your hands. As per price, if you just need a laptop for emailing and the Internet, well, costs have come down. Competition among PC manufacturers have brought Dells, Toshibas, Lenovos, and others come down to $350-500. Decent pricing to same the least.
Why stay away from a laptop? The very reason why it’s a plus is also a negative. It’s portability also causes its parts to be less than helpful when coming to replace them. Everything is miniaturized to fit the frame. As such, all major components, such as the CPU, video graphics cards, USB ports, and other parts are all on the motherboard. If one part fails, the motherboard needs to be replaced since these parts are on the board together. This is a computer service repair nightmare.
Why go with a desktop? They are generally faster than laptops, price to price comparison-wise. The reason to stay away from a laptop gives an edge to desktops. All parts are replaceable. Plus, most parts can be upgraded versus laptops that are limited in this scope. This is a desktop computer repair plus. You can buy a desktop and stick with the same monitor, keyboard, and mouse, along with peripherals.
Why stay away from a desktop? Lacking space? You need a spot for the tower, monitor, and keyboard/mouse. No space, no good. Or at least you can go with a low profile, slimline desktop.
In the end, to summarize here, if you have the space and don’t need to be mobile, go for a desktop. If you’re not going to keep it long and want the coolest, shiniest toy, go for a laptop.