Anything that would make the USA more democratic and fix all the problems with elections.
The system isn't working and needs to be fixed.
Of course, another problem is war. Any amendment which would make it harder to go to war would meet with my approval.
edit: btw Supreme Court justices should have limited terms. Lifetime appointments don't seem prudent. (although I don't think we need a constitutional amendment for that, that was just a tangent I wanted to consider)
The Constitution already makes it hard to go to war, Congress since WW2 has given up that power to the president
