I love (hate) when someone (me) buys a moneylender or two, and never gets a chance to use it, thanks to his opponents discard attacks...
Of course, substitute any other card into that sentence.
As a group, we love Dominion because every game is different. You don't know which cards are going to be available, so the only advance planning you really get to do is during setup, right before cards get shuffled. And because each game is different, each game 'feels' different. One day you might have a good set of trashers, the next you'll be action-poor, while the time after that, everyone went big money (whether it was a good idea or not...). No one is an expert at all of the cards, so each game challenges everyone, and in a different way.
For myself alone, this game appeals to me in the same fashion that Star Fleet Battles does: Lots of tactical play, lots of combinations, and everyone can pick a style of play that best fits them.
There is only one thing I dislike about Dominion: 5 players. We tried that yesterday, too slow. Ok, and Swindler, but that maybe because my son seems to have a laser sight for my best cards when he plays that one...