In short, the 3 I's: Innovation, Invention and Individual Initiative. Capitalism is great about inventing new products. In fact in the book "Monopoly Capital" by Baran and Sweazy, two radical economists, they answer the question "How does capitalism survive?" by saying that it's the technological revolutions that allow capitalism to keep reinventing itself and giving it new life. They mention things like the railroad, the automobile, television. Well, I think that's all to the good. No other economic system provides as well the incentives for people to be entrepreneurs. Any new economic system would have to provide the same incentives; otherwise you would have stagnation. That's the problem with socialism. No one wants to take a risk. Everybody just wants his paycheck for the least amount of effort.
Preferensism would have to let people be free to innovate and invent if it were to be a viable system. Entrepreneurship is vital to an economy. However, it need not be carried to the lengths it is in contemporary capitalism in which every successful entrepreneur becomes a billionaire. The power of corporations needs to be checked - especially their hiring and firing power because this is where they really have power over the fortunes of those who just work for a living. In Preferensism each person would have an equal share of economic power. Instead of employer-employee relationships people would all be essentially contract workers, including managers and executives of large corporations, and thus on an equal footing.
Inventors would reap the intellectual property of their inventions, and that property would carry with it financial rewards just as in capitalism. There would be an incentive to invent, and not just to be a "worker." That's where socialism has gone wrong. There's too much emphasis on just being a worker. I think everybody should be in business for him or her self. If he or she works for someone else, it should be on a contract basis. Then he or she is an equal. Workers, especially union workers, expect "benefits" from their employers. This is just too paternalistic. They should buy their "benefits" in the market place just like everyone else. Of course, this is where society is heading. People are being forced to provide their own pensions rather than the company providing them. Same with health care. Only problem is the stock market's a casino. Some will win; some will lose. Powerful corporations, in collusion with government, control health care making sure the average citizen pays through the nose. This is why society as a whole, not individual employers, should provide health care and pension benefits. Well, social security is something, but not much.
I think it's good that people are taking more charge of their own lives. Their assets include whatever degrees and credentials they have. They should be able either to be in business for themselves or rent their own labor out to a corporation on their terms. The problem is a lot of degrees only prepare you to work for somebody else, not to be in business for yourself. This puts you at a disadvantage. People need to wake up and smell the coffee. A lot of college degrees are worthless. Unless they qualify you to set up your own shop, hang out your own shingle, deal with your own clients, you are totally dependent on the good graces of some employer. Once people are no longer willing to be subservient in the employee role, they will gain greater self-respect, and they will have greater control over their own lives.
For more on this see Social Choice and Beyond.