1. Set corporate tax rate to 0%.
2. Tax all dividends and capital gains on individual returns as regular income (ie no preferred lower rates).
All corporate profits eventually show up on individual tax returns one way or another. There is absolutely no logical reason to tax corporations except out of some kind of progressive hatred of, and need to count coup on, corporations.
My plan eliminates corporate tax preference for debt. Eliminates numerous distortions from political meddling in corporate tax structure. Eliminates double-taxation problems. Eliminates double taxation of foreign corporate income. Levels the playing field between C and S corps. Eliminates the practice of corporations keeping two sets of books (one for tax authorities, one for investors) which is a common practice. Saves a ton of money on tax preparation and compliance, essentially eliminating a whole class of taxes.
Once this is done, then we can start working on simplifying and taking out all the distortions in the individual tax code.
Update: One could go on a length discussing the hypocrisy of the current corporate tax system. Basically it has become a vehicle for each party to reward its favored constituents and punish its enemies. The Obama administration's current tax plan is a great example. Obama wants to reward manufacturers, and manufacturers only, with special lower rates because they are, err, much cooler somehow than other businesses. But it turns out that most of those supposed tax subsidies that Obama proposed ending for oil companies are just the same breaks all manufacturers currently get and he wants to increase. So is he now going to say we need to favor all manufacturers except oil companies with special tax breaks? And he wants to encourage investment and R&D, except in the oil industry (which happens to be one of the larger sources of capital investment and R&D spending). And what ever happened to the notion of equal treatment under the law?