The BNE flight has recently been reported as running half full in J (which should make upgrades easy). The daytime flights are definitely lighter in J/F as they are very impractical for business travel. No idea how SFO loads are, but I would expect better upgrade chance than out of LAX, however this is only one flight while LAX has up to 6 flights per day (so total chance is greater ex-LAX if you can switch flights).