26. Border Village
It's just village! But you can get your 5 with it, hey, that's pretty nice - you often would just be buying the 5-cost anyway, they are very often better than what you can do for 6. And village really isn't bad, especially by the point you can get to 6. And it has really nice interaction with cost-caring trash-for-benefit.
25. Grand Market
These things can snowball out of hand, but it's a pretty significant overrate here - it's to get (even in engines, it's a bit slow, particularly as it 'just' gives you a bunch of free money and buys without elongating the game), and often you can just do at least almost-as-good things anyway.
24. Ill-Gotten Gains
So the IGG 'rush' is good, we all know. And a lot of times it just stomps. But by itself, that would only make this a good card. The real issue is that it's not much worse than silver for BMish decks, so you can get some provinces with it in the meantime.
23. Governor
This is a notoriously difficult card to play. The card draw is way the best thing on it, but with the worst penalty, you have to be careful. It does degenerate things, which makes it high, but the ability of the opponent to do likewise limits this guy. The traditional gain-golds-with-it, trash-them-later is reasonable but not great, but just throw this into an engine and it's a non-terminal utility card. Important that drawing 5+ times with it is not a huge deal if they haven't set up multi-gain ability - you are 'only' guaranteeing them a province.
22. Stables
It's a net lab, except you also get to trade your worst treasure (usually copper) for a random card. And it cycles faster. This makes it net better, except it might totally fail. Basically the answer is that you can't spam as many of these as you would labs, but generally this is still a little better.
21. Fishing Village
Squire for actions now is actually not that good. Bazaar next turn is amazingly strong. Ok, it misses a lot of shuffles, but... such a good card to have, and verrry cheap. This would have been higher earlier, but there have been many other good villages recently, which somewhat hurts the relative value of this guy.
20. Vineyard
The best alternate VP card. Okay, probably colony? But this is just super strong on any board with a remotely spammable action, bonkers on boards with gainers (particularly non-terminal ones). Fairgrounds is another set of provinces? This is most often even more - okay, you can only get so many at once, but it's worth it.
19. Torturer
A super stackable attack. Sometimes you can just eat the curse, and in hand of course helps. Sometimes there's no village. Sometimes there's strong trashing. And sometimes there's another curser. In these situations it's a little bit better (occasionally slightly worse for certain reactions/draw-to-x) than smithy for 5, which is nothing special but not terrible. And in almost all other situations, it's ridiculously dominating. You do have to watch out for 3 pile endings sometimes, which people don't always get, but it doesn't come up all that often anyway.
18. Counterfeit
This card is good in virtually any deck you want to play. It's very good in most of them. Engines are probably the obvious bit. But even in big money, it's generally quite a bit better than gold (at least the first one, often two copies are). Go ahead and trash that silver or gold - the game isn't lasting long enough to feel the pain of it much.
17. Upgrade
The card is basically an anti-Sea Hag, if you think about it for a second. Okay, not really, it's basically upgrade. But where hag adds a card, this takes one away. But it's also a cantrip. And it can turn cards into better ones later on - being spammable is huge for it, and there's at least gold to turn into after the clear-out. Really good in engines, not that bad in BM (except terminal draw). This qualifies as strong trashing.
16. Margrave
Militia attacks are really good, you know? So are smithies. And this gives +buy, which puts it over the top. It doesn't stack well, really at all, but most often, you can get 1-2 of these and then something else, and it's quite good. And even a stack of these isn't so bad - they get 3 good cards, but unless they have margraves themselves, you probably don't care *that* much.