The Edge's color rendition is way, way worse. There's a lot more to quality images than MPs. Tom's has a great comparison they dropped today, if you want to see what I mean.MSRP on the Galaxy Edge is $1100. The Air is just releasing and already there are trade in deals with carriers for people who have not upgraded their device in a while (AT&T is giving me $840 in billing credits for trade in of my 14 Pro with a busted screen).
The Edge definitely has a better camera.
The Edge battery actually tested worse in the EU certification testing regardless of claimed performance, it is rated for more charge/discharge cycles which is important for those who keep their phones for a long time.
Size wise the devices are almost identical... you point out that the Edge is slightly thinner but it is also slightly wider and longer to accommodate the larger screen. I believe it also might have done worse in drop tests (scoring a C where the Air scored a B).
The Edge is a good device, but I don't want to run Android.
I'll miss the wide angle lens, but I'll live.