17th is just as bad.
I find that arguable, however, it is the IRS who are in the news and most detested now. Seems to me that the 16th, without which the IRS would be of no need, is the best and most effective amendment to attempt to repeal.
If the funding dries up, the federal government will be forced to retreat back inside the Constitutional cage our founders took great pains to ensure contained it.
The secretive Jekyll Island machinations at the start of the last century released it through the eventual passage of the 16th and 17th ammendments.