What tax plan would you advocate?

That is the problem. There are a lot of potential tax plans which would make sense. But tax plans are not determined by experts. They are determined by politicians who make compromises and try to get advantages and earmarks for their constituents. So any plan I come up with, will never get enacted unless lobbyists with obscene amounts of money to spread around support it. Even then, it will be riddled with loopholes because the other guys with money will have to have their needs met too.