I voted for "The Visitor" because I just love the depiction of the father-son relationship in DS9 - and this is a perfect example of it.
But it was a close race, and I didn't vote for ItPM because I knew beforehand that it would win. *g* Actually, I didn't really like that episode all that much when I first watched it, but it grew on me, and right now I love it. Interestingly, this one poll is the one out of all 5, where the 3 candidates are actually 3 of my favourite episodes as well (contrasting ENT where none of the 6 who made it to the most current vote are anywhere near my top 6)...