It's a year divisible by four, so discussions of voting in American politics are inescapable. Four years ago I wrote about how not voting can be an important social signal and about who voters are actually negotiating with. This time I'll point out that people actually have more than one vote, at least in the U.S., and fully legally -- because they can turn out other votes. So the question of what they should do with "their vote" is silly.
First, some basics. An activist is someone who takes action in order to try to cause some political effect. Activists are generally not hired to do this, which is what differentiates them from professional political operatives, but that's not important at the moment. In the U.S., there are two main paths for activism: non-electoral activism and electoral activism.
Activists generally want to have the largest effect that they can, so they usually end up looking for multipliers to their individual effort. The classic multiplier is to become an organizer of other people. So a non-electoral activist goes from participating in protests to organizing protests. An electoral activist goes from attending rallies to activities like volunteering for a candidate or party's ground turnout operation.
The U.S. has something like 40% of its eligible voters not vote, so there's a huge pool of voters to turn out. Each voter who would not have otherwise voted but whom you got to the polls produces an extra vote that would not have existed if not for your efforts. So each person potentially "has" a large number of votes. How many votes can a volunteer expect to turn out? I'm not familiar with the technical aspects of this, since I'm a non-electoral activist, but here's a sample article. I imagine that a volunteer might be able to turn out 100 votes or more.
So all of the endless agonizing about who to vote for, whether it's moral to vote or not vote, whether you have responsibility for the action of voting or the inaction of not voting, is all kind of beside the point. People who are seriously committed to having a measurable impact on this process have long since decided what to do and are doing it. If electoral activists were boasting among themselves about how many people each of them turned out, that would be fine: activists get little enough reward so that a little boasting is a good thing, and it would probably quickly turn into an exchange of technical details among the group that would help each other. But the discussions of how to use an individual vote are pointless and usually deployed simply for moral leverage. They reduce an issue to individual virtue: is someone a good person or not for doing an almost entirely symbolic act.