The Apple iMac all-in-one (AIO) has long been the darling of photographers and videographers, thanks to its combination of sleek design, excellent performance, and its affinity with content-creation tools like Adobe Lightroom, Photoshop, and Premiere. For these folks, the new Apple iMac 21.5-inch with 4K Retina display ($1,499 as tested) is a welcome addition to the Mac desktop lineup, with its 4K screen, fifth-generation Intel Core i5 processor, and updated peripherals. Outside of this admittedly popular niche though, the less expensive Lenovo B50 remains our top pick for midrange AIOs, thanks to more memory and storage, an HDMI-in and -out connector, and more conveniently placed ports. And if you have the budget and the space, the latest 27-inch iMac with 5K Retina display is our Editors' Choice for high-end all-in-ones. 

Design and Features
The exterior of the iMac looks identical to the 2014 model, with the same aluminum and glass body. It measures 17.7 by 20.8 by 6.9 inches (HWD) and weighs 12.5 pounds. But turn on the system, and the main upgrade becomes very apparent: the display.

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The 21.5-inch Retina display is the real star here. With a resolution of 4,096 by 2,304, the In-Plane Switching (IPS) screen has 4.5 times the resolution of a 1080p HD display. That means you can have four 1080p HD video windows playing at native resolution simultaneously, or you can fill the screen with a 4K video from your iPhone 6s or other sources. Unfortunately, most of what you see will likely be self-created, since 4K video content is still rare at this time. Note that, since there is less physical space, the 21.5-inch screen has 9.4 million pixels compared with the 14.7 million (5,210-by-2,880 resolution) on the latest Apple iMac 27-inch with 5K Retina display. That's still a lot more screen real estate than the 3,840-by-2,160 resolution you'd get on an Ultra High-Definition 4K display like the ViewSonic VP2780-4K.