Dominion - Rio Grande Games
Dominion, including all of its many expansions, is probably the most played game in our house, and has been for years. This is the game that really set off the deck builder mechanic craze. It is such a simple mechanic too: use the coins in your hand to buy cards that give you more spending power or other game effects (like multiple buys or attacks that force your opponent to discard cards) or victory cards. The trick is knowing when to buy what - buy those victory cards too soon and you end up with a hand of green unable to act, effectively slowing down your progress. The game ends when the most valuable victory cards have been bought up (or any three piles of cards are depleted).
Although this game is so great, not all the expansions fit everybody. My oldest daughter does not like attack cards - for her she'd prefer a game of competitive solitaire. Also we have a few friends who don't like the more complicated (wordy) cards of the later sets - so they are happiest with games from the basic set and maybe some simpler cards thrown in. Personally I like them all, but I'm less enamored with some of the more vicious attack cards in the Intrigue expansion. Also it is pretty much the consensus among my friends that Alchemy is their least favourite expansion (even though I quite enjoy it). With all the options and well themed expansions Dominion is sure to remain a staple of our gaming for years to come.
One other thing worth noting, there are some great digital tools for helping you shuffle up a great selection of Dominion cards from all the expansions you own.
Likes: Tremendous replay value, easy to teach, complexity can scale to players abilities and preferences quite easily.
Dislikes: With all the expansions this is a beast to lug around.
Fun: This game is always fun, even when you get a combination of cards that makes for a painfully long game, winning is just all that more satisfying.
Quality: We use our game constantly, and the cards show it. We've also taken the game with us to conferences where new players are less kind to components. But I have to say that the cards have held up very well. Also the other components, like metal tokens, are of amazing quality. Kudos to Rio Grande for production value.
(re)Playability: Every game of Dominion is different! This is probably the biggest reason that we keep playing this game over and over.
EDIT: Right after posting this I found out about Dominion Adventures. Picked it up and we've taken it out for a spin. Right off the bat we were disappointed with the quality of the cards. They are thinner. Some of the new mechanics are great though, not sold on the events, but the variation on duration cards is quite fun. But I'm still not happy with the component quality.
EDIT: Since this time we picked up Dominion Empires. I think this the best expansion to date. Card quality is back to the original. Events have grown on me. The debt mechanic actually adds something that feels new to the game. Also I am able to get all of the cards into the base box and the alchemy box (no room for more though) and I have a smaller box for the rule books, player mats, and tokens. Much easier to lug around.