With your interest in elite status and international flights, you're probably not interested in WN or B6. WN's FF program is not very good for long haul fliers (it racks up award tickets quickly for the short haulers -- e.g. weekly trip to RNO or LAX/BUR/SNA -- but a long haul flight gets the same one point each way that a short flight gets). B6 has a lot of OAK-JFK flights, though. Both WN and B6 have their main presence in the bay area in OAK.

UA has a huge hub at SFO, so it has a lot of flight selection from SFO. Try to make elite on UA if you want to use them, though -- the non-elite UA @ SFO experience is not particularly great (long check in lines, long lines at security, less seat pitch than WN or B6 in non-premium economy, lots of weather delays at SFO (granted, being elite won't help the weather, but may help in rebooking if you plans are messed up due to the weather delays)). I found that redeeming UA miles for an award ticket was much harder than redeeming AS miles for an award ticket (same end points, same days of the week, same time of year, different years).

AS is mostly a west coast airline. Their main advantage is that they have mileage partnerships with AA, CO, NW, and DL, making mileage collection easy if you fly a lot of different airlines. An award economy ticket in the contiguous US states on AS is only 20,000 miles, instead of 25,000 miles that most airlines' award economy tickets (or AS award tickets on partner airlines) in the contiguous US states cost. If you choose UA as your primary FF carrier, you may want to use AS as a secondary FF program to collect mileage when the best flights for your trip are on a non Star Alliance carrier.