I can knock.....
Wings for its disks access. Unlike PCs, Hard Drives for Amiga's were a luxury. It is not good enough for programmers to say "yeah we know there is a lot of disk swapping, but if you installed it to a Hard Drive there would be none" IIRC Knights of the sky can be installed to the hard drive as well and it can be a multiplayer game as well. Not that I had the hardware to test that out.
I didn't have a hard drive for my Amiga, I got the machine when I was 11 and by the time I was 16/17 it was broken there was never a time when I could have afforded a hard drive.
I prefer Knights of the Sky for the reason that you could go anywhere. The learning curve was good. It started off fairly easy and you quickly moved your way up the kills table and missions were fairly simple. BUT as the war got on and as your rep grew it became harder and harder. I don't think I ever managed to get to the end of the war.
Wings was a fun game but the inability to go anywhere and the fact that you had to swap disks a lot between games made playing it not so great.
Knights of the Sky had a nice intro as well, brilliant little piano piece which suits the period very well.
Knights of the sky was the most complete game and I suppose how much you enjoy each of the two games in question depends on what you look for in games. In flight games I think I look for realism and freedom more than restrictive gameplay and cartoonish graphics.