Modern USB Wi-Fi Adapter Examples
Some examples of current USB Wi-Fi adapters include:
An entry-level N150 USB Wi-Fi adapter, which is quite affordable and can be found for around $10. The Trendnet TEW-649UB is an example of this. However, it tops out at 150 Mb/s over 2.4GHz and cannot access the 5GHz band. For basic use and slower Internet connections, you may find this more than adequate, however.
The fastest USB adapters are rated for AC1200 speeds, and they're available from most manufacturers. An example is Netgear's AC1200 WiFi USB 3.0 Adapter (A6210). It features a high-gain antenna that flips up to increase signal strength. It purportedly achieves speeds of 300 Mb/s over 2.4GHz and 900 Mb/s on 5GHz. You'll find it priced around $50.
The D-Link AC1900 Wi-Fi USB adapter is an upcoming product that should enable even greater performance. It is due out this spring, and promises a speedy 600 Mb/s over 2.4GHz and a blistering 1300 Mb/s on the 5GHz band. The D-Link AC1900 Wi-Fi USB adapter expected this spring will feature even faster speeds than what are currently available.