Book and KD both account for just under 40% of the teams turnovers. As is stands Booker leads the team in turnovers:
Devin Booker has the most turnovers for the Suns this season with 175 turnovers.
www.statmuse.com
However, you can't look at turnovers in vacuum. For example Anthony Edwards is #1 in turnovers but his plus minus is still +225 when he is on the court. Book on the other hand is #3 in turnovers and his plus minus while on the court is -104.
Anthony Edwards has the most turnovers by a shooting guard this season with 217 turnovers.
www.statmuse.com
Similar story with Durant. Tatum is #1 at his position with the most turnovers but his plus minus is +443 when on the court (by the way that is downright sick and shows how much impact he has on his team). Durant is #3 like Book but his plus minus is -8 when on the court.
Jayson Tatum has committed the most turnovers by a power forward this season with 186 turnovers.
www.statmuse.com
This seems to say that Book is hurting us on the floor much more than Durant. The fact that they are both top 5 in total turnovers and their plus/minus is both negative would seem to be a double whammy. However, it appears Booker's turnovers have been more costly to the team. His plus/minus is much worse than Durants.