
Games Workshop (GW) has released win rates by faction for the last 60 days of Warhammer: Age Of Sigmar competitive play. Only about half of this data reflects on the new General’s Handbook, as it has only been out for about half of the 60 days.
The results are in the image below. The Bonesplitterz faction was not included as GW says there wasn’t a statistically significant amount of games played with that army.

GW says they believe the Gravelords and Bonereapers are at the top of the pack due to having, “a good cross-section of units to choose from, which are all viable.”
Kharadron Overlords and Gloomspite Gitz are now back in the target “sweet spot” of 45 to 55%, due to changes in Battlescroll: Andtor.
GW also reports that the new General’s Handbook has changed how Battle Tactics are scored, taking into account rewarding not just what a player accomplishes, but how they dedicate resources. Due to this, they are concerned it may pose an extra challenge to factions like Skaven, whose tactics are divided up among their clans.