Fultz looks like the best prospect right now, his ability to create offense is elite. He can get his shot off against anyone or set his teammates for easy buckets. With his length (6'10 wingspan) and athleticism give him the tools to be a great defender, but he hasn't shown the defense you want so far.
By the time the draft comes around, I predict that there will not be a consensus. It happened the year Okafor came out, and I expect it to happen again this year.
As a fan of the current Celtics team, I'd rather Boston ends up with Jackson, Tatum, or Monk instead of Fultz. I like what we currently have at pg, and I'd rather not draft a player that forces change at the position.
Jackson, Tatum and Monk are all capable of plus shot creation at the next level and that is our biggest need long term, imo. Jackson does it with ball handling and athleticism, Tatum has a deadly face up game from the triple threat, while Monk can score off the ball, in transition and in the pick and roll.
Short term, Tatum and Jackson could give us wing minutes and long term I could see either pairing well with Brown. Monk fits very well next to Smart and could be a long term replacement for Bradley if he wants the max in the summer of 2018.
I trust Tatum, Monk and Fultz as shooters. Tatum might not be shooting the 3 at a high percentage but his free throw percentage is almost 90%. Draft studies have shown that college free throw percentage is more predictive of NBA 3 point percentage than college 3 point percentage.