If I were assembling a track and field team, Julio would be my top pick between the two. He's faster. Can jump higher, faster, is stronger, etc... The one thing I think Cooper has on Julio in the athleticism department is his agility, and that's why he's able to run such good routes. He can turn on a dime.
Julio ran a 4.39 at the NFL combine on a broken foot.
ON A BROKEN FOOT.
Julio could play almost any position on the field, Cooper couldn't.
Cooper is the better WR, but Julio is the better overall athlete.