There is not, and will never be, a best candidate. Some coaches will be better at systems, some at forging a common purpose, some at holding players accountable, some at recruiting better players into SLC. What Smith/Ainge want from the culture will matter.
That also means that skin color will also be factor in a league where most players are not white, for as long as SLC has a perception as being more racist than, e.g., Chicago (note that I said perception). For some players, it will alleviate concerns that management will be indifferent to their struggles and difficulties. That will add some value to the head coaches tenure. No one is saying skin color should be the only factor, but it's even more foolish to pretend it should not be a factor at all.
