3 incorporates some really interesting mechanics into the franchise, like carrying more than one object at a time, but has an odd plot. Still a very, very good game.
1 and 2 are linked story wise. They're both super solid games, although 2 takes a fairly long time to get you into the meat of the game.
Really any of them are a great choice. If you only pick one, I'd recommend 3, as it has some great features, and you don't need to worry about catching up on the story.
Just sweet jesus stay away from the Wii one. It's pure POISON.