Sullinger has more value because is a proven commodity just needs to shore up some personal habits. Not listening to your team and producing vs. not listening to the medical staff and staying permahurt, I would take the former.
The difference is, if Embiid ever did get healthy, he could be a superstar.
There is zero change of Sully ever being a superstar, and the change of him eve being an All-Star is pretty slim.
Both guys have issues that would potentially scare off other teams, but teams are always going to be more willing to take a chance on guys with star potential.
Just look at Oden, Bynym, Brandon Roy, Grant Hill, Penny Hardaway. Despite chronic injury risk, somehow those guys always managed to find SOMEBODY willing to take a chance on them.