We haven't even seen Simmons play yet breh.
And regardless, Giannis is the way to go because his length, defense, fastbreak ability, scoring touch from the inside, and vast improvement in a short time just makes him seem like the all around better player. He has top 5 potential with the way he's improving, I have no idea if Simmons will have that.
Better thread would be Embiid vs. Giannis.