There is a debate between proponents of the Flat Tax and the Fair Tax.
The Flat Tax is a good idea and is better than the current system. But I think it is only the second best tax system we could have:
Under the Fair Tax, everyone will pay voluntarily when they buy goods and services. When the rich man buys his yacht, he'll pay it. No loopholes. When the illegal immigrant buys his beer, boom box, car, whatever, he will pay it. No dodging because his income goes unreported.