> I'd rather "lose" than throw my vote to a person I disagree with about everything... I don't think that's a rational decision.

Unfortunately, in this world, a rational individual would balance policy with likelihood of winning. In other words, pick the lesser evil.

For example, let's say you have three choices:
a) X, with whom you completely agree, but will not win
b) Y, with whom you disagree over many issues, but might win
c) Z, who is a brutal totalitarian madman, who might win

If you chose X solely because of "basic integrity", I'd argue that is not rational. I'd also be delighted to play poker with you.

Unfortunately, due to the voting systems in many countries, you end up with tactical voting. Most unfortunate.