Alternative to AT&T DSL in SF?

I used to pay 19.95 for 6Mb/s, then they raised it to $40, then they raised it to $43, and this month they raised it again to $50.75. I'm NOT paying $50 for 6 megabits, especially with all the disconnects I'm getting. What alternatives do I have here in San Francisco? I've already looked at Comcast, any other ISPs I should know about?