Clue, hands down. Best game ever. Awesome post and happy A-Z blogging.
As a kid my fave games were Game of Life and Cluedo, I do still like board games but its hard to find people who share that interest, but when I nag them into submission, I like to play pictionary, rapidough, scattegories, hum bug and that one where you have to describe a word without using certain words. I don't know if these count as board games? So will say Scrabble instead.
I think my favorite game of all time is Balderdash - my family has a huge game day every year and that game is always hilarious. The definitions just get more and more outlandish as the night (and the drinking!) goes on. :) But also Clue - great game. Oh, and Stratego! Haven't played that in a long time. Gonna have to go dig out my games now... :)