A bit late to this one.
By every industry definition, Karl Strauss is indeed a craft brewery. They are a regional sized (aka large) craft brewery with one large production facility in San Diego that produces the vast majority of their beer. All their brewpub locations (aka restaurants) have brewing equipment on site which produce a small amount of the beer on tap (one brewer usually brews at 2-3 of the pubs - at least that is the case for the LA/OC brewer).
As far as breweries in LA County, it really depends on what you are looking for, but some of the best beer producers would be Monkish (Torrance), Highland Park (Highland Park) and Beachwood (Long Beach). Firestone Walker's Propagator outpost in Venice is good too, but I'd consider Firestone Walker more of a Central Coast brewery than an LA Brewery. Other good ones would include Mumford, Cellador, El Segundo, Smog City, Ladyface, ect.
Orange County also has quite a few very good breweries. I'd suggest Noble, Green Cheek, Bottle Logic and The Bruery/Bruery Terreux (disclaimer: I am biased about the last one).
