Okay, so nothing here was more than three spots from my list, and only one card was even that far off. That card is Wharf, which I had all the way down at #6, below Torturer/Minion/Hunting Party. Torturer is debatable, I think with hindsight I'd have put Wharf above it since boards where you can skip Torturer are so much more frequent. I guess Minion is sort of the same issue, in that unfavorable boards also occur with Minion, but it's far less commonly a bad buy than Torturer (even when the classic Minion engine isn't a possibility, it can still cycle and attack with aplomb). And if there's support, Minion works just fine in Colony games. Hunting Party I am quite confident is better than Wharf, however.
I mostly don't agree with WW on which cards are too low or too high, but he's totally right about Lab. I had it just above Stables, because it's useful in a wider variety (read: Treasure-light) of decks, but really the two are almost identical in power. Conversely, I had Stables a couple spots higher, and Margrave is another one I had a bit higher as well; it's equally powerful in both BM-X and in engines, where it supplies three count 'em three crucial functions: attack, Buy, and Card. Granted, if you stack a bunch of Margraves then the attack becomes pretty lame, but it's a great kicker if there's other +Card as well.
Guess I'll also defend Mountebank as #1 over Witch, where I went along with the crowd. For me, the most important factor is that you can ignore Witch far more often, like over twice as often, than you can ignore Mountebank. Of course, the situations where you can ignore either are pretty uncommon. But if you have a board with strong trashing and strong engine possibilities, it may be better to just build your economy and drawing fast, since you'll be able to Remake or Chapel those Curses as they come in. However, since Mountebank gives two cards instead of one, it's nearly twice as hard to outrace him: those Coppers do often make a huge difference. A lesser point is that I much prefer +$2 to +2 Cards here; if you have other actions in your deck that's less a chance they collide, if your deck is clogged with Curse and Copper (like Mountebank gives you!) then your expected value is higher with the cash now. And, not that they're always reliable, but Councilroom stats prefer the Mountebank, it has a marginally higher Win Rate, lower Win Rate Without, and is bought just a bit more often. Yes, a second Mountebank is much weaker than a second Witch, that's true; in a match which is really just "give out all the Curses ASAP, buy money and Duchies" then maybe Witch is better on the head-to-head. But on balance Mountebank is simply more disruptive, so it gets my vote.