Macs and Windows PCs are available in all three of the major desktop form factors: mini PCs that can fit on a bookshelf, sleek all-in-ones with built-in (and usually high-resolution) displays, and traditional desktop towers that are bulky but have room for more expansion. These three forms each have strengths and weaknesses, and none of them is an obvious best choice for everyone. You'll have to choose based on what you plan to do with your desktop and where you plan to put it.  For truly cramped quarters or light workloads, as well as for people who love the efficient use of space, a mini PC could be the best choice. They come in sizes ranging from tiny sticks not much larger than a USB thumb drive to small-form-factor (SFF) towers that may be nearly a foot tall but have compact footprints. The smallest sizes have the benefit of disappearing behind an HDMI-equipped monitor or TV, and they contain a processor, memory, storage, and ports to hook up keyboards and mice. They're economical and power-efficient, and they can serve as adequate web browsing or multimedia viewing platforms. But know that the models at the truly tiny end of the scale have no room for adding extra internal components, and their preinstalled parts are usually difficult or impossible to upgrade.  Regardless, you can find a fair mix of what qualifies as mini PCs that can be customized or upgraded with better components. They're bigger than the "stick"-style PCs but much more flexible and expandable. Traditional tower desktops are capable of even more flexibility but also bring a lot more bulk. Nowadays, the differences between midsize and full-size towers are less well-defined, and some of the new PC case designs—from cubes to glass boxes—defy easy categorization. Still, nearly all desktop towers have generous amounts of interior space and full-size (a.k.a. ATX) motherboards, so you can install one or more (sometimes, many more) secondary storage drives, more RAM in empty slots on the motherboard, a video card if one isn't installed, and in some remote cases, even a second graphics card for extreme gaming or graphics-accelerated tasks. (Note that not all desktop mini towers and towers can take a graphics upgrade. That is where reviews come in.) An all-in-one (AIO) desktop is quite a different animal from both of these form factors. An AIO can save you some space since the display is built in. An AIO's value proposition comes down to space saving and whether you happen to be shopping for a desktop display at the same time. Though you can find budget AIOs with basic feature sets, lower resolutions, and non-touch screens, many new models include touch-enabled screens, and some AIO panels have exceptionally high native resolutions of 4K (3,840 by 2,160 pixels) or even 5K (5,120 by 2,880 pixels). Touch displays make them excellent choices for watching movies or serving as a multimedia hub in the kitchen or other public areas of your home, though the absolute highest resolutions target content creators rather than consumers. With a few exceptions for business-oriented models, you will give up a lot of room for expansion in an AIO versus a traditional desktop tower. Cracking open an AIO for an upgrade or fix, while not impossible, is a bigger deal than opening the side of a desktop tower. Apple's recent iMacs are particularly difficult to open.