The ending of Annabelle: Creation explains that the demon, not the doll, is the real source of the trouble, and it ties Janice's fate to the start of Annabelle (2014). Esther's confession is the key: she and Samuel unknowingly invited a demon into the house when they begged to see Bee again. Linda throws the doll down a well and the evil carries on regardless, which supports that reading. In my opinion, that is the smartest rule the film sets, because the doll becomes a vessel and a lure, and the grief of the Mullins couple becomes the open door.
Sister Charlotte then locks Janice and the doll inside the closet to contain the demon. Janice escapes, is adopted under the name Annabelle and later murders her adoptive parents, which feeds directly into the 1967 prologue of Annabelle (2014). So, the Janice storyline is the bridge, and the farmhouse is where the doll's reputation begins. It could be argued that the film is also a quiet tragedy for Janice, a child who is hurt by the demon and then used by it.
The closing tag scene points toward The Nun (2018), and that demon later turns up in the saga as Valak. As for whether Annabelle: Creation is connected to The Conjuring, it is, through the doll: the Warrens handle a haunted doll case in The Conjuring (2013), and they lock the same doll in a blessed glass case in Annabelle Comes Home.
Which Annabelle is scariest? Perhaps this one, in my opinion. The demon wears Bee's shape and preys on a girl disabled by polio, which gives the farmhouse scenes a cruel logic that the 2014 film, with its cultist break in and nursery, handles more quickly. That is taste, and a fan of the earlier film's opening could reasonably pick the other way.
