LBJ vs. Goldwater.
I was a college student of the 1960s variety. I hated (and very rationally feared) the Vietnam war and the draft, but I voted for LBJ because I was sure Goldwater would be worse. I'm still sure I did the right thing.
So I've voted in a lot of national and local elections by now, and in the vast majority of them, my preferred candidate wasn't on the ballot. But I chose the least of the evils, or the best of those available, as the case may have been. I don't regret any of my votes.
My fellow liberals often rejected that position and either didn't vote at all or voted for a third-party candidate. In 1968, that gave us the vile Nixon. In 1980, that helped give us the viler Reagan. In 2000, that contributed to giving us the vilest of all, Bush.
I'm more convinced than ever that I did the right thing in the past, when I voted for the best, or least objectionable, Democrat. I'll continue to do that.