It depends what you are expecting out of your stopover. If it's just a connecting point and bed for the night, then SJC will likely work out as the easiest/cheapest. Immigration queuing will be minimal compared to SFO, and hotels are likely much cheaper. Just that there isn't anything to do in the area. For restaurants etc you'll either need to take what you can get in the hotel or take an Uber out to Santana Row or something like that.