Hi Ulli - lots to like here also - think I might prefer the HA on the first one also. Id be tempted to crop a little off the top.
Could have increased the ISO to enable you to stop down some more - would have given a bit more DOF - SHARP were it needs to be!! might have helped with the back half of the bird.
Like the low shooting angle and good detail throughout!
I also like the "stare you down" HA's in most cases but here there's not quite enough eye contact (with his head angled down) so I also prefer the first one. Lovely movement in the water...