I am going to be flying from Madrid to San Francisco and have the option to connect in Frankfurt or Newark, NJ. Any thoughts on which would be a better airport for a connection? Lay over times for both options are right around 3 hours and total travel time is very similar (within 45 min one way or the other). I've flown to and from both of these airports, but never connected through them. How is immigration at EWR? Decent? Total mess?