Let's wrap it up with a conjecture based list of synergies and antisynergies.
Way of the Chameleon
S: Any virtual Money (esp. Poor House)
S: Lab variants (and Horse givers)
S: Cantrips, when there is too much draw already
S: Any source of + Cards actually, to avoid reshuffles
S: Opposing Enchantresses
A: Steward (as in: more stiff competition)
A: Drawers that don't use "+ Cards"
Way of the Rat
S: Cards that scream "get the most of this ASAP", especially Grand Market
S: Cards with a "while in play" effect, especially Highway
S: Villages, to grant the terminal space
S: Throne Room variants
S: Donate
A: Most cards really prefer to be played 99% of the time.
A: Treasureless decks
Village Green
S: Tactician
S: Sifters, especially Embassy and Dungeon
S: Cards like Loan and Rebuild that search for non-Action cards
S: Opposing discard attacks
S: Gainers, to increase the density of this card
A: Lack of above makes its extra effect mostly irrelevant (though not entirely)
A: Strategies that don't care about Villages (like, god forbid, Smithy BM)