SFO is full of 1Ks and a GS members. If you are gold/silver its basically winning the lottery to get upgraded. Even at Platinum/1K its luck of the draw.

Since DL/AA do not have SFO hub its easier to get upgrades overall, but routing may not be as good.

I am on track to hit 1K again this year, but will likely match to Delta or AA then move most of my flights over after March. The new mileage program is one thing, but also having to suffer the constant service cuts is a whole another thing. At least with DL or AA I have better in-flight experiences.