Diadem>Masterpiece
As already discussed, Taxman. For this specific case, there's also Mint (can't mint a Diadem).
In order for A > B to be true (barring the universal edge cases), we need these to be true:
1. A and B share the same card types, which matters for Tribute and Jester.
2. A and B are not Treasure cards, which matters for Taxman.
3. A
can do everything that B does, or else you will sometimes prefer B to do its special thing.
4. A does not force you to do anything that B doesn't also.
3 prevents a coin token card from being better than a standard virtual coin card, because you may prefer the virtual coin when using Black Market. Same goes for a card B that has you discard when card A doesn't, due to Tunnel.
4 covers a lot of stuff you might not expect. If it forces you to draw or even reveal an extra card, that can be undesirable for reshuffle considerations. If it forces you to attack, that can be bad because your opponents may have reactions that benefit them. If it forces you to play an extra card or to topdeck something, well there are situations where you don't want those things either.
4 doesn't cover
extra coins (virtual or token), because having more money to spend never hurts you. It doesn't cover extra buys or actions for the same reason.