... to get the most knowledge possible...
From the classes I've assisted with, this depends on you as much as the shop and instructor. If you put out the effort, you will get the knowledge and skills with any decent shop and instructor.
We're spoiled here because there are lots of great dive shops in So Cal, and everyone has their favorites. Personally I'm biased toward my own LDS. I suggest you call around, talk to the shops to get an idea of what they go over, how long the OW cert class is, what is included and what you're responsible for. The $100 OW cert class can easily end up costing more than the $700 OW cert when you add in all the things that are extra, so make sure you compare apples to apples. Doing the e-learning can reduce the amount of time you spend in a classroom.
If you go with a dive shop that does the certification over two consecutive weekends, with the second spent in Catalina, geography becomes less of a consideration. You could pick the dive shop you feel most comfortable with, get a cheap hotel room nearby for the first weekend night when you're doing classroom and pool skills, because the second weekend you're out at Catalina anyway, so no need to be limited to nearby dive shops. If you're planning on diving in So Cal, in the long run you have to end up somewhere by the big ocean to the west of you, so one or two weekends driving to the coast pales in comparison to how much time you will spend diving if you really get into it
For the OW cert, if you go the beach dive route instead of Catalina and/or boat dives, if conditions are crappy (yes, that does happen on beach dives here) and you drive out to the coast but you don't get the requisite number of dives in, you will end up spending more time driving to the coast over several weekends than just getting all the certification dives done in one weekend.