A lot of people think that Applejack is boring because unlike Twilight, Rarity, or Rainbow Dash, she doesn't have a clear goal or destiny to fulfill. I don't think this is the be all and end all of what makes a character interesting, and this video sums up why. If you haven't checked out Clover Keen's videos on YouTube yet, I highly recommend you do so!

http://www.youtube.com/watch?v=S0TytQtnwFc

Clover Keen's channel