Given that, I don't think it's a realistic choice and I think the real alternatives are a flat income tax and a national sales tax. I favor the former.
I don't like the notion of making businesses into tax collectors. At least with the IRS, there is ONE AGENCY that everyone can hate. It helps keep it in line. But I'm afraid that a sales tax would become quite insidious and much easier to increase.
And I go the other way, because I don't like the notion of individuals having to report their private finances to the government. As long as there's a determination of "income" as the basis for the tax, there will be an invasive, intrusive IRS checking your personal financial information to determine if you're complying. A flat tax would also not get rid of hidden, VAT-style cascading of taxes.