Looking at options on a fall trip I find Icelandair with a 55 min transfer. I know that's what they do at KEF and it's worked for me before but not quite this tight.
Then Delta has a direct to Detroit with 2.5 hours to do US entry stuff. Never done that at Detroit so don't know how it goes but figure it's got to beat Atlanta
And there's an Air France with 2 (or possibly 4) hours to do whatever needs to be done there. Then US entry at Denver (not bad usually)
Haven't checked out respective quality of flight service, Icelandair is (or was) fine. Think I did Air France once and don't have bad memories but in any event this is our first overseas since Covid and I figure anything is pretty much a new bet.
Thoughts or pertinent experience welcome.