If WiFi N is fine for you I recommend the Cisco WUSB600N V2. It's a dual band USB stick based on the RaLink RT3572 chip and works like a charm with Debian. I used some of them in the past for several years with no issues.
If you need 802.11ac I guess the support is not very good yet with Debian. I "upgraded" my WiFi sticks to new AC ones based on the Mediatek MT7612 and I have frequent disconnects. They almost work, but still not at 100% Hope this helps. Miguel A. Vallejo
