I've spent a couple days researching what is the best USB wifi adapter to use in wireless penetration tests/site surveys.
If you are only concerned about the 2.4ghz spectrum than the widely suggested ALFA AWUS036H is still the best and works flawlessly out of the box.
The problem arises when you are trying to encompass both 2.4 and 5ghz ranges. I'll save you the rant about my search for the right device and i'll just give it to you here:
The only Dual Band (2.4/5ghz) USB adapter that works out of the box with everything including WPS cracking (reaver) that you can currently buy is the Ubiquiti SR71 USB Adapter. It comes up as the carl9170 driver in BT5r3.
Hopefully this saves you the days it took me to figure out which one is the best.
After some extensive testing i've noticed that it sometimes has a problem with WPS cracking and can be a bit finicky with the drivers. The ALFA AWUS036H still works flawlessly. I'm going to be testing more and more devices and will report when i have something.