Great game.  Really highlights the idea of simplicity and fun.  Sure there are more complicated board games around, but this one you can pick up in 30 minutes and teach to an 8 year old.  By the end of the hour, you will feel like you are racing to build your train route across the United States while competing with your opponent.  There's a reason this game is so good.  Children love it, Adults love and you will too. Not sure about all the others, but this is the one that started it all.