I still think the best tax going is the estate tax.
It's not a tax on already taxed money. It's a tax that basically allows government to recover from the deficit spending that is inherent in governmental operations due to their answering to the people:
-"we have money in the budget!" -govt. "well spend it on something for us already!" -the people
-"we don't have money in the budget!" -govt. "well now is no time to be taking things away from us!" -the people
An estate tax allows government to recover from this cycle. Not by taking ANYTHING away from anyone who worked for it mind you, but by preventing their heirs from disproportionately inheriting sums of wealth that are so vast, many never need to work a day in their life to be set for life.
This money could be plowed into government to erase deficits (which reduces the debt service line item in the budget), fund necessary programs like Social Security, Medicare, etc.
A strong estate tax that hits say, anything above $5M in wealth but carves out an exception for real estate if the heir makes it their primary residence, and taxes the rest at 75% would be more than fair. $5M is more than enough head start in life.
Coupled with tax policies that reduce taxes on businesses, but eliminate deductions on high individual salaries AND bar options as compensation (stock and restricted stock only - which has a fair value on the date awarded and avoids loopholes in compensation taxation that options get around), add more brackets above the current top bracket, and maintain the lower brackets of the TCJA, there could be a start to funding a middle class recovery. The key is right now, there is no ability for shareholders to vote against outsized executive compensation packages. However, if the business were subject to a larger tax liability because the executive's salary wasn't tax deductible as a business expense beyond a certain point, then it would pit the shareholders against the executive taking so much of the pie in a more robust way.
Besides, all economics are trickle up anyway. Would this fix income inequality? Maybe a little. Would it fix wealth inequality? Of course not. The majority of people will still spend everything they have and be stupid, and the rich will still get that money in the end anyway, but it will have been taxed a few more times on the way (generating deficit reduction), and you'll have fewer people struggling due to circumstance and birthright than you do now. In essence, the country would still be stupid, but it would be more fair. More meritocracy is what I want to see. Birthright shouldn't determine someone can float through life and be fine no matter what, nor should it mean one bad decision in life sentences you to a lifetime of poverty with no opportunity for parole. Just my 2c.