My experience is similar. Currently I'm using Linksys WUSB600N v2 USB dongles based on Ralink RT3572 and they work just fine. They can handle my 100 MBit conection using 2x2 N mode in 5 GHz band without too much problems.
But I have also a Linksys WUSB6300 802.11ac dongle, based on RTL8812AU. Although I made it to work, all drivers/modules I tried seems to be in very early stage to my taste, with many missing functions: a lot of missing information while running monitoring programs (like wavemon). So, I'm also looking for a Linux friendly 802.11ac USB dongle. Greetings
