Fultz by a country mile.
In the NBA today the 3 point shot is king. Fultz can really shoot it, Simmons can not. Fultz is great at creating offense for himself, Simmons looks to pass more often than not.
Our offense is centered around 5 out spacing that stretches the defense. Fultz stretches the defense, Simmons does not. Fultz has value off the ball as a shooter, Simmons does not have value off the ball.