Are there other flights later to AMS if you miss your connection?
Is it very important that you arrive in AMS on time?
If there are no later flights to AMS or if it's very important that you make the flight to AMS, I would opt for the earlier flight out of SFO. Since you're a 1k you can spend the extra time in the RCC so it won't be that bad. Otherwise you can take your chances with a tighter connection. At least in ORD (assuming it's all on UA metal) you won't have to transfer to a different terminal and re-clear security.