#5 is the best. The composition (leads the eyes with the flow of bikes), motion (every boy), warmth of the sun rays, the tranquil atmosphere of city park (the fresh greenery, those people on the bench), mood of challenge (thanks to the 1st boy), and "the air" - enough empty space in the image.

This one, I had a feeling, can benefit a lot being converted to monochrome. What will you say?..

bw is worse, honestly.