Don't think that Delta will be back this year unfortunately, as I used to love their EDI/Atlanta flight. They have a horrible habit of doing absolutely zero advertising for new flights which then struggle to achieve near 100% load factors.
My call would be the EDI/EWR route on Conti. It might be cheaper to fly via Schipol on KLM, but you have the hassle of being at the airport at least four hours before you actually fly over it going in the right direction. Plus there's the potential luggage transfer problems at AMS as well.
If you fly direct to EWR in the US, I can confirm the immigration & customs folks there are were really quite chatty & personable. At least they were about 18 months ago when I was last there.
I used to do a weekly EDI/EWR/IAH/EWR/EDI stint back & forth to our headquarters for various projects about once a month, up to a year past September & always found them quite friendly & helpful. Since then, the furthest I've been is a day trip to Aberdeen. I doubt the boss must think that I kick her dog on a regular basis or something, as the rest of my workmates have kept up their travel & some have even expanded to Rio...
The good thing about going through EWR as well is that in clearing customs you have to re-check your baggage, so you can confirm that it's made it as far as the US. Secondly, the actual re-checking process is dead easy.
Unusual - I know.
From the gate, along to the end of the corridor, down the escalator into the immigration hall. Queue up & hand over your docs. Get fingerprinted, & photographed, passport stamped then down another escalator into the baggage hall, pick up bags from appropriate belt along to the left hand end, through customs, down the ramp hand over your bags & back up the escalator for security & transfer between terminals. It's never taken me more than 20 minutes from landing to be through all of that & be back airside ready for my connecting flight.
