Almost certainly UA/CO. They fly their own metal nonstop SFO-HKG/SEA/EWR.
If you really want to fly out of SJC, AA might be better as you can earn EQM on AS nonstop nerdbird SJC-SEA and can connect in ORD/DFW for other destinations in the US, and then fly out of SFO on CX when you head to Asia.