So we play a game that has what (?)......seven editions and going on an eighth, along with about a thousand offshoots and a bazillion house-ruled variations...but I'm going to suggest that anyone not already playing a preferred game...or maybe in this case anyone trying to figure things out for the first time...that they should play B/X.
Now I'm not going to try and go into the history of the game because that's been done several times far better than I'll ever be able to get into. There's a lot of history before the introduction of B/X and far more after the history of this edition.
While history is part of the reason I suggest new players start with B/X, which I'll get into in a moment, it isn't the main reason, and I think a lot of people being introduced to D&D/RPGs would inherently use "history" against choosing B/X.....
....think about it. You can find the current edition of the game easily, at Wal-Mart even, but B/X? Well that isn't so easy to get ahold of for those not in the know. Here are two places you can start: