NM said:
If you connect in the USA, ylou have to go through USA immigration, collect bags pass though customs and recheck for the onward flight. So both LAX and SFO are going to be similar in the process.
Similar in process but a world of difference in terms of ease.
Main direct airline options are AS, UA and AC. There may be others.
At LAX QF->UA is T4/TBIT->T6/7/8. Straightforward but a bit of a walk.
At LAX QF->AS is another terminal change (to T2 IIRC, again a wee distance to walk).
At LAX QF->AC is T4/TBIT->T2. Security queues at T2 can be bad, also a bit of a walk.
Connections in reverse direction are easy, but need time for inspection of your checked bags.
At SFO QF is international terminal. Immigration generally easier than at LAX, at least in my experience. Both shorter queues and (much) more pleasant officers.
UA is one side of domestic and AC on the other (both quite close to where you come out from international with UA being closer to the *A pier and AC closer to the non-*A pier). I cant recall where AS uses, think it may be the far side of domestic?