Jaylen Brown.
Tatum is going to get most of the attention, and rightfully so, I do think he's the team's best player. But when I take a step back and look at what Brown has done in his career it's pretty remarkable. Last season he was 25-6-3 with an eFG% of 56%. He scores from everywhere, defends everyone, and balls out in the playoffs.
This season he's going to be a priority in the offense like never before. I can't wait to see what he does.