I'm going to make a list out of this:
12. Adventurer - This card, honestly, I never found it useful or fun to play. I don't even understand how a card that draws 2, and not even actions, was priced at 6. Yeah, it skips over victory cards and it doesn't get actions if you have none, but as draw it is weak and it doesn't do anything else. Also, it doesn't work well without (treasure) trashing, but those horrendous victory cards don't need to be trashed to make it even semi-useful. There are so few cards who cannot trash victory cards but can trash copper.. (I think Adventurer still is worse than, let's say, Margrave if it would cost 5.)
11. Sabouteur - Ugh. Slow to resolve, slow to play, not good if you play it yourself and not good if someone else plays it. This card is only annoyance and enormously slow-paced. I played it in 4p once, it wasn't fun. It just wasn't. As much as I love Swindler (the game-changing aspect of it makes it one of my 5 favourite cards in all of dominion), Saboteur doesn't get any of this love.
10. Thief - Just not fun. I honestly only like it somewhat as the chapel payload destroyer in situations with no virtual coin. And maybe Thief-Gardens. Other than that, I just don't think the card felt ever fun or useful.
9. Scout - Another instance of a very poor card, this and Adventurer are clearly the two worst cards ever printed. But Scout at least is fun. You get to arrange some cards, get annoying victory cards out of the way. And in mono-intrigue games it can get to the point where it goes from very bad to 'meh, maybe it is not so bad after a-- oh it still is not good enough'.
8. Spy - A slow-to-resolve cantrip that is Scrying Pool without the coolness value. It is bland and I honestly don't think I have ever seen a board where I thought 'Spy is a killer card here, man'. At least it sometimes can be good, but this is one of those 'yeah a fun card but if it was never printed I don't miss it'-cards
7. Great Hall - Same as Spy, but I at least like the double card type-concept of this card. It was maybe too easy, but not all cards have to be hard to understand. In the end, it did add too little, like my #6
6. Woodcutter - Suffers from the 'too easy'-problem, but also from the fact that it is almost always the worst possible option for +Buy. It is an option, but really, only Herbalist is worse usually. The only reason I rank this at 6 is Woodcutter-Gardens, which was much more fun to play that Workshop-Gardens in my base only days. But now we have Squire-Gardens and Beggar-Gardens, so who cares about Woodcutter-Gardens.
5. Secret Chamber - This is the good part. Fun cards to play with unique concepts. This unique concept is probably where Secret Chamber goes wrong. Its reaction is fun, but it is seldom game-breaking and furthermore, can be somewhat confusing. The discard option is all right but not interesting, it is the reaction part that is fun. The largest reason is that it makes topdeck attacks much less worthwile. Just put that estate on top when your opponent tries to Swindle. Sadly, usually it just prevents those attacks from being bought, it doesn't help Secret Chamber to be used more often.
4. Feast - Procession/Feast is awesome. TR/Feast is great. But that's the largest part of the fun. Buying a 4 to trash it and get a 5 is only nice if one doesn't need that silver, usually. Still, the card idea is the thing I like. Sort of like mathematics in Innovation. (But that is actually a huge card)
3. Tribute - Still not the most memorable card, but I think it is fun to just play something and see what happens. It is dicy, but can be very good. Randomness in the game can be fun, as long as the games are more casually oriented.
2. Chancellor - Back in the day this was a pretty unique concept. Chancellor is also one of the few cards that doesn't face from poor opportunity cost or the fact that it is unnecessary; it is strictly better than silver providing one has the actions to spare. Also, it is a fast card. It speeds up your own game and the wording doesn't slow the game down. The only problem is Scavenger, really.
1. Coppersmith - Just because Coppesmith is the most unique card and it is fun with large hands. Just playing an action and saying 'well that's +7 coin' (in the end, at least) feels really great. It was too strong with TR/KC in my view, but that was also really fun in a sense - copper worth 4 feels pretty crazy. It was somewhat the problem of this card anyway; either it is completely hopeless (in boards without possible large hands or boards with (copper) trashing), or really good.