It's election year in my country and we'll be choosing our next president through the traditional two-round system.
The two major contenders this year have both very high rejection in part of the electorate, and this rejection is usually manifested by supporting the candidate which is most likely to defeat the rejected candidate in the second round.
I wish it was possible for voters to manifest their disapproval more directly, through some kind of negative voting schema. For example, if candidate A gets 50 votes for and 30 agains (net 20), Candidate B gets 40 votes for and 10 against (net 30) and candidate C gets 30 votes for and 5 (net 25) against, the second round would be against B and C. Since the second round is a binary option, negative votes count exactly the same as a vote for the opponent, so negative voting wouldn't be necessary.
I know that there's an infinite number of potential voting schemas, and not any of them is perfect, but I believe that simplicity is a must for any system that invites participation from all of society and just voting against someone is a lot simpler than ranking, or quadratic votes or whatever.
While we're at it, maybe we could improve somewhat the fact that the power is too concentrated in the hands of the President: maybe a 55/45 victory could give less power to the President (versus, say, Congress), while a 90/10 landslide would give them broader powers and less checks. Let's ignora for a while the risk of unreliable elections: even though I live in a(n ever) developing country, I'm fairly confident in the trustworthiness of our elections, so not too worried about this for now.
P.S.: After a quick googling, there seems to be a Taiwan-based group for this kind of voting and Disapproval Voting is the name of a related, but different system.