Zerker greaves
Im not really good at adcs, but from my understanding, long range adcs (kog?(depending on W CD, id have to ask a main about this, trist, caitlyn jenner, and ashe should all buy zerker greaves. This is because they are supposed to be using their range bonus deal as much as possible to targets.
Heros such as lucian, mf (although might not be needed since she has a huge flat MS boost) and sivir are better off with swift boots because they rely on getting close. In a sense graves and corki would too, although they might benefit better from greaves (added burst) and MPen boots, since their kits are unique. Ezrael could benefit from anything but greaves, depending on team he is facing