Plagued is great for the board and combat control it brings
I dont think the Grief / Ephemerate package is necessary for Reanimator, but it does seem easy to include and hard to justify not including, particularly given how strong Ephemerate is with Archon of Cruelty and Ashen Rider
Quick Study earns its place on this list with its ability to be played at instant speed, a weakness of its classic counterpart, Divination
Necrogoyf Necrogoyf gets its own spot because it has even more graveyard synergy than the other goyfs
When they enter, their last abilities will each trigger three times (once for each of the other two tokens, and once for itself.) If the original Securitron Squadron is still on the battlefield, its last ability will trigger three times as well
Then, you mill yourself five cards and reanimate a creature from your graveyard to play