The Intel drivers require blobs. Broadcom used to require blobs that you had to cut out of Windows drivers yourself, though I have no idea what that's like now.
The vendors use the excuse that this stuff requires FCC certification, and if they expose the low-level stuff some hax0rs will turn the wi-fi portion of the spectrum into CB radio circa 1979.
The OpenBSD guys used to recommend Atheros, because the specs were open. I have no idea what the current wisdom is. I run Thinkpads, which are BIOS-locked to only Lenovo provided cards, so I've been in iwl-land for a long time.