Sonic runs on AT&Ts lines. It was slow and had lag spikes. After about a year it got to be where the modem (and Internet) would cycle for a couple minutes about once every 2 hours. The (Sonic!) tech came out, found a fault on the line, and his advice was to get Comcast.
I also tried getting Wave, but couldn't.
I went through a similar runaround with my previous building (also in SF), where I tried to avoid Comcast. Eventually I caved.
Comcast was terrible and shady from the very beginning. They sold me an internet package they later claimed didn't exist(!) even though I had the offer in writing from the sales guy. So they just adjusted my bill to what they thought I should pay.
They eventually backed down after I kicked up a huge fuss (and took it to social media), but they also threw a bunch of free stuff I didn't want in to my package as "compensation", and guess who was paying for that when my promotional rate expired before they promised it would? My rate was constantly going up if I didn't fight them tooth and nail. I had to check every bill and almost every one had a new surprise. I have never worked with such a perfidious organization.
So after all that I wanted Anything But Comcast, which I already disliked before that experience. I've seriously considered tethering to Verizon Wireless as better...
But I like to do online gaming and Comcast is the only vaguely reasonable option at this point. They're a little less shady if you avoid ALL television service.
EDIT: OK I suggested sharing a T1 but apparently that hasn't been a good deal since the 90's.