Right now, I'd say Josh Jackson would be my pick. At #3 you can not make a mistake and you have to get a player that will contribute. Everyone is saying the Sixe biggest need is outside shooting -- and that is correct -- but they also have an opening at SF.
IMO, Jackson is the safest pick. His game checks off every box as either "very good" or "excellent", except outside shooting. Athletic ability, ball handling, defense, rebounding, coach-ability, character, hustle, run the floor.... check, check, check, check .....
Even if Jackson does not develop a better outside shot, he still gives you an extremely athletic 6'8" SF, who gets you 12-15 PPG based on running the floor, 5-8 RPG, 1-2 steals per game and provides very good defense vs. other team's SF. IMO, worst-case scenario for Jackson is that you draft a very reliable, very good defensive SF who will be in the league 10 years +.
I'm not sure the other candidates at #3 are that reliable.
I too think Jackson at #3 could be the most reliable. But I certainly would not give him a "check" for character. Hit and run of a park d car and then threatening to beat a woman. Not something you brush over and say he just has great character.