Dominion is the game that invented deck building and remains the purest expression of the mechanism. The card variety across base set and expansions creates enormous strategic variety. The solitaire quality of the mechanism — you are primarily optimizing your own deck rather than interacting with opponents — is sometimes criticized but is actually what makes it scale well to higher player counts.

Intrigue added attack cards and reaction cards that increased interaction. Adventures added duration and reserve cards. Prosperity added the Colony and Platinum cards that create a different scale of game. Seaside added the duration mechanism. Each expansion adds genuine design innovation rather than just more cards.

For groups new to deck building, the base set is all you need for many sessions. Add Intrigue once you want more variety. The full expansion collection is only worth pursuing if the mechanism is your primary board gaming interest.