Equality works best.
As our wealth gap grows, our longevity shrinks. (The biggest predictor for the health of a nation is the wealth gap. A large gap destroys social cohesion creating a ruthless and highly stressful society. Even rich people don't live as long!)
One way to create a stronger and larger middle class is to start doing something about corporate salaries. They're doing this in Europe, particularly in Holland. As the report says: "Europeans have become too accustomed to living in relatively equal societies to tolerate American-style executive pay."
You not only need a minimum wage, but a maximum wage as well.