This is another card categorization post. Someone mentioned in the Dark Ages previews that Scavenger was an upgraded Chancellor, and that was odd, particularly since the $3 and $4 cost tiers aren't greatly different from each other. But there are a number of card-with-a-bonus cards, including at those prices, and I thought it would be interesting to try to enumerate them all.
To qualify for the list, there must be some card Y that does all the good things some card X does, plus more, with no additional drawbacks. That's not quite restrictive enough, because I don't feel like Market is a Pawn-with-a-bonus card or that Laboratory is a Wishing-Well-with-a-bonus card, so I'm going to use some reasonable judgment to prune the list down to what feels right.
Improved $3 Cards
Silver - Royal Seal ($5), Stash ($5), Harem ($6)
Chancellor - Scavenger ($4)
Woodcutter - Nomad Camp ($4), Bridge ($4), Festival ($5)
Workshop - Ironworks ($4), Armory* ($4)
Village - a long list of oft-discussed and well-understood cards I need not reiterate here
Improved $4 Cards
Smithy - Torturer ($5), Rabble ($5), Margrave** ($5), Catacombs ($5), Hunting Grounds ($6), Nobles ($6)
Remodel - Expand ($7)
Throne Room - King's Court ($7)
Militia - Goons ($6)
Young Witch - Witch ($5)
Peddler*** - Market ($5), Bazaar ($5), Treasury ($5), Highway ($5), Junk Dealer ($5), Grand Market ($6)
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It's really interesting how few cards there are on this list, though there are a lot of pairs of cards that don't quite qualify here, like Secret Chamber/Vault, Lighthouse/Fishing Village, Market/Grand Market, and Spy/Scrying Pool.
In particular, note the utter lack of improved $2 cards. I'm certain it is by design that the $2 cards tend to do unique things (Embargo, Moat, Beggar, Pearl Diver, Crossroads, and Haven, for example) so that they will be worth buying when you want those effects.
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(*Most benefits have edge cases that turn them into drawbacks, but it's worth pointing out that Armory is not nearly as good for Gardens rushes as Workshop, even accounting for the price difference.)
(**Here again, Margrave's attack can be a penalty but is generally a benefit.)
(***Peddler doesn't cost $4, and in fact its price feature means that Peddler itself is a "Peddler-with-a-bonus." I include it here only because "Peddler-with-a-bonus" is an understood and useful term, and $4 is generally accepted as its balanced price point. But if you want to be a stickler here, call it "Oasis-with-a-bonus." Then people will tell you that Oasis is like a Peddler that activates Tunnel, so it ought to be the other way around anyway.)