The gist about USB wireless cards would be, "A strange game. The only winning move is not to play."
It's usually cheaper and a lot more reliable and performant to get a simple concurrent dual-band AP (wireless router with OpenWrt) to cover the wireless side, rather than wasting your time with USB wireless cards which will never work well enough. Depending on your needs both replacing the wrt3200acm or continuing to use it wired-only with a cheap mt7621 based AP attached would be the options.