I don't think Fultz is the only guy in tier 1. Tier 1 is Fultz, Ball, Jackson, Tatum. I'm happy with any of those 4. Obviously the No. 1 pick has the most trade value, but it's unclear as to who will become the best player. In fact I would not be surprised if Frank Ntilikina turns out to be the best guard in this draft, better than Fultz or Ball. Ntilikina has a 7-0 wingspan and is terrific defensively.
Fultz also has a 7'0" wingspan.
As a contrarian myself yes you can find random people who put someone above Fultz, but I'd guess 90% of all draftniks see Fultz at #1 for a few very good reasons, such as having elite athleticism even for the NBA, being able to score at all three levels, and being able to run an offense (particularly a PnR offense) and control pace.
The other three you mentioned (and Fox for that matter) all have warts. Ball, I've mentioned. Tatum and Fox, everyone knows their issues. Jackson is older, had a lot of success playing the 4 at Kansas but isn't built to play 4 at the NBA level (he's at least 20 pounds lighter than JB and has a lanky frame)., and has a short wingspan (6'9.75"). and has shooting questions.
I suspect that if any GM had to start a team from scratch, they'd all take Fultz.