i'd keep #1 and throw the others out. it's a bit centered, which i don't like, but this could be a good stock image, as it's against a flat blue sky (no cloud) and could be chopped into any photo montage. i'd crop it a bit tighter using the rule of thirds and you're good to go.
I like 1, 2, and 4 the most. 3 and 6 would have looked real nice if it was zoomed in a bit more. 5 could have been zoomed a little more as well to capture the birds at a closer angle.