Netgear's A6200 wins the award for most ambitious industrial design. Its USB interface is mounted on a hinged connector, and its antenna is housed inside a thin rectangular bar that you can pivot to fine-tune its reception. If you're a frequent traveler, Netgear's antenna design is much less fragile than the Asus USB-AC56's screw-on antenna (unless you take the time to remove the Asus model's antenna every time you pack it).
When I tested the Netgear adapter with its USB cradle and its antenna in a vertical orientation, its overall performance fell short of that of the first-place Asus USB-AC56 by just 2 megabits per second. But I saw a big gap between first and second place when the client was in close proximity to the router, separated by 9 feet: The Netgear delivered TCP throughput of 310 mbps whereas the Asus delivered 404 mbps. The A6200 placed second when the client was in the kitchen, too, delivering throughput of 312 mbps versus the 347 mbps that the USB-AC56 achieved.
The Netgear adapter proved to be superior at longer ranges, on the other hand, delivering TCP throughput of 233 mbps compared to the Asus's rate of 163 mbps when the client was in my home theater, 35 feet from the router. And when the client was in my home office, 65 feet from the router, the Netgear delivered throughput of 264 mbps to the Asus's 213 mbps.
The A6200 measures nearly 5 inches long when its antenna is extended (not including its USB interface), and slightly less than 3.5 inches long when the antenna is folded down for travel. The USB interface pivots, but it doesn't fold away completely as the one on Buffalo's WI-UW-866D does. The adapter has a WPS (Wi-Fi Protected Setup) button that makes it easy to connect to a router that has the same feature.
The A6200 is one of the more expensive adapters that I tested in this group, with a street price of $70 (the same as the top-performing Asus USB-AC56 and the decidedly inferior Linksys WUSB6300). If range is your most important requirement, I'd recommend this adapter over the Asus. If your client PC will typically be located in close proximity to your 802.11ac router, however, the Asus USB-AC56 should deliver higher performance.
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