Atheros is my favorite, they seem to have the best support, there are a few chipsets that aren't supported, but they aren't really common. I've had good luck with Ralink and Intel too.
Broadcom hasn't always been great, but they've released some closed source drivers for many of their cards which does work well, the open source driver can be a little tricky to get working because you must cut the firmware from the Windows driver to make the card work.
Remember, Linksys, Netgear, Belkin...etc... do not make wireless cards, they make the plastic junk that goes around them. The stuff that matters is inside.
Last edited by elliott678; 03-31-2011 at 07:34 AM.