There are three occasions in life that I tend to regretted in terms of voting.
I regret voting for Ross Perot in 1992. I realized about a year later that he never really wanted to win....this was more about punishing Bush, than anything else. All of us wanted a third-party guy option....sadly....it was a fake option that we got.
I regret voting for Senator John McCain in 2008. It was a stacked situation, with your choice for the GOP of being McCain, Romney, or "Huck"....while on the Democratic side.....it was a choice of Hillary in her youth, or a unknown Senator from Illinois who simply gave good speeches but had no real experience. It was for me....the most worthless election in my life.
I regret voting for Romney in 2012. Again.....a stacked election with no options from either party.