Who do you think "A" is?

I am a big fan of Pretty Little Liars...those 4 girls on a mission to find out what happened & who murdered their friend, well, they just surprise me every week! It took me a long time before I liked Spencer & I'm not really sure why but her character seems less overacted this season.  Emily kind of annoys me, she always has...its something with her mouth well Shay's mouth that bugs me but I like her storyline so I work through it & I'm really curious what is going to happen with her dad. 

So, back in the early stages of the show I thought "A" was Ian but then as time went on & he was murdered I started thinking it was Melissa but now I'm thinking it just might be Mr. &/or Mrs. Hastings or perhaps someone we haven't even met yet.  I am curious as to who other people think it is...any ideas?  We'll find out the true identity in 2 weeks but after seasons and seasons of wondering who it is I'm really hoping that when we find out we are shocked.  For a brief minute I thought it was Mona but now that she's being harassed I'm guessing it isn't but really I think I need to stop thinking about it & just wait but waiting sucks!