This should be right up there with Monopoly, Scrabble, Risk, Stratego, and so forth as a Classic American Game. It's easy to learn, easy to play, and has tons of strategy. Also, don't be put off by the "horrible" production quality of the most recent edition. It plays just fine, as do the older versions. The gameplay is what shines here; you don't need big plastic toys to appreciate it.
A board game masterpiece that belongs in every collection. But which version?
--Classic Avalon Hill Bookcase (1968-1976) - This is my favorite edition. The black tiles on the yellow (or brown) board offer a stark contrast for easy understanding of the board. Plus, the box is nicely compact.
--New Avalon Hill Edition (1999) - This one is highly sought-after, but I don't think it's worth the cost. The little buildings are nice, as are the much bigger board and tiles, but that means it also takes up a lot more space.
--Hasbro/Avalon Hill edition (2008) - A bare bones printing where they substituted cardboard chits for plastic tiles. The game is still playable, but you lose that tactile feel.
--Newest Hasbro/Avalon edition (2016) - Similar production to the previous entry, but with a changed board (10x10 instead of 9x12) and other minor rule changes. Avoid.