Do you need pci, pci-E or usb? Want N300 or is 54Mbps OK?
RaLink, prior to being purchased by MediaTek, provided hardware specs to FreeBSD. For usb, pci and pci-E, anything RaLink is usually good. Mediatek is less so.
For pci-E, I also have good performance with rtl8188ce,
One caveat is the little usb nano adapters all look the same but have a multitude of different chipsets - Make sure you have an easy return if dmesg does not concur with what you tried to buy.
Another solution which may be better is to grab a router/ap/device that supports OpenWrt and use it as a transparent bridge (wifi --> ethernet) if you prefer open source.
Most Range Extenders also supports this type of operation if you want to use vendor firmware.
A little late in my reply, but I bought the device listed at the above link. It took some finagling and a crash course in how WiFi works on FreeBSD, but I now have it working. It works quite well in fact.
So to everyone who responded, I thank you for the time and effort you put into your answers.