I'm a frequent LAX-SFO flyer and chose WN for the co-terminal access during delays. I've been on delayed SFO flights due to flow control more times than I can count. On WN, if the delay is over 30 minutes, I can waitlist onto the LAX-OAK flights for free. I've been successful on getting the next OAK flight about 2/3 of the time. Yeah, it sucks to take Air-BART to get to BART, but better late than even later I suppose and BART travel times are comparable.

Well, I also chose WN because of the lack of cancellation fees and that RR2.0 is decent for my travel patterns.

I guess terminals are not much of a consideration, other than I try to minimize my time there.

I have to admit, I have not taken AA on this route, just DL and UA. I've used UA twice this year on the 6a from SFO-LAX and both were complete fiascos. I have been delayed no more than 20 min on SFO-LAX 6a flight.

Anyways, my $0.02. Hope it helps