About the thing rrenaud measured, while I find that statistics incredibly interesting, I would make two considerations when interpreting it:
First is the skill difference already mentioned, I find no surprise at all that Goons is first there, because if one player can't properly build an engine and the other can, the second one should have an almost 100% win rate against the first, and a lot of games of Dominion (specially online) are played with two players on opposite sides of that skill threshold. If you take only games with people on the same side of side threshold (but with still a difference in skill) I believe the difference of expected win rate with Goons, against expected win rate without Goons should be much lower. Other cards like Chapel and Donate also should have similar behavior. (even though turn 5 Chapel Syndrome and an exacerbated player 1 advantage with Donate are totally a thing).
The second point, which I will illustrate with completely arbitrary percentages is as follows: Suppose 10% of Dominion games you have the luck factor being considerably favored towards you, 10% of games towards your opponent and 80% of games the luck factors somewhat evens out between the two players. Now suppose I play against Dan with a card like Village, for example, I might win maybe 50% of the games where luck favored me, 25% of games where luck evens out, and 1% of games where luck favored Dan, now if that card was Black Market or Tournament, I would suppose these percentages might look a lot more like this: I could win maybe 90% of games luck favored me, 10% of games with even luck and 0% of games where Dan got lucky.
So overall Dan should win more often against me in games where there are BM/Tournament than in games with Village, but I would still say that BM/Tournament are swingier cards, because they tend to make getting lucky matter more, it's just that they being somewhat hard cards to play properly leads to the better player winning more often on the vast majority of games where the luck factor just isn't that big.
Sorry for the made up percentages, they're just a means to express my idea, I have absolutely no idea if they would be even close to correct.