Schedule (not the time at home, but the actual arrival times of flights and equipment, especially depending on what cabin you are flying in, are important factors). SLC-AMS is the best option. It is probably a codeshare of KLM on a 787 which is a nice ride and the AMS is an easy and reliable connection. International flights provide better service than domestic flights, so more time on the international flight is better. CDG is fine if things go smoothly, but if AF decides to strike or you have irrops, its a nightmare.