AF
Your assessments are a little too glib, first off, just about every player in the first round is going to be a one and done player, so you can't look at them like they are finished products, they are all 19 year old kids.
This idea that 3-8 are all the same is a bit of a misnomer. Jackson is the 3rd best player in the draft, and he might have the potential to be the best player in the draft when all is said and done.
Tatum is going to be a good player, but he is not a fit for the Sixers. He is a half court player that needs to create his own shot and is a below average defender at this point. See Okafor...
Fox and Smith are nice point guards who need the ball in their hands, but again, the Sixers are going to play Simmons at the point, so you really need someone who can play off the ball and make shots.
Monk is the one player that fits need the best, but his size is a bit of an issue, but to say he is not a great athlete is completely off base, he is a great athlete. Other than his size, he can jump out of the gym, and is the best shooter in the draft. I think his size (he is at least 6' 2", it's not like he is Mugsy Bogues) would be less of an issue on the Sixers than other teams. With Simmons, Embid and Saric, he will likely get a boatload of open looks.
Isaac is the most intriguing guy in the draft, but very, very raw. I don't think he works for the Sixers because they already have too many question marks.
I think there are two choices, if you want to take the best player at 3 (assuming Fultz if off the board), then take Jackson, if they want the best fit, take Monk, and if Jackson goes 2 to the Lakers, I would still take Monk over Ball.