reading more about it, you're right. i always figured that since broadcom was so widely supported by multiple aftermarket firmwares, that it was the most mod-friendly. guess it was just the most throughly reversed :/
Broadcom is absolutely the worst, because it's the most open-source-unfriendly. It's only had a lot of reverse-engineering attention because it's so ubiquitous (not just for routers, but for laptops too), but it's all no thanks to Broadcom.
Atheros and Intel I believe both have good open-source support.