Fluttershy I love animals but people scare me somtimes, im not antisocial! it's just well, I don't feel comfertable around new people that's all...
I'm deviating from the question just a bit. Instead of which pony I relate to the most, I'm seeing how much I relate to everyone of the mane 6. Lets start off with my personal favorite, Rainbow Dash For starters, we're both one of the more athletic ones in our circle of friends. We could care less about our looks. Similar to Dash, I can be a bit stubborn, but I always pull through for the team in the end. Now, on to Twilight Reading. Did I mention I like reading? I also have a HUGE bookshelf. I'm pretty smart when it comes to Social Studies and Science etc. Now, for Pinkie. PARTY! YEAH! I LOVE parties. ALthough i'm not nearly as good as singing then pinkie, my friends do call me hyper active. A lot. On to Fluttershy. I LOVE animals. Espicially dolphins. I mean, how is it possible not to like dolphins? Anyway, I can be a bit shy at times. For example, If i'm in a room full of people I don't know, i just hang around and listen into conversations to see if anyone likes the same stuff as me. Applejacks turn. I'm a really hard worker, and I enjoy being outside hiking, or camping etc. For Rarity, I can say I relate to her the least. There is one thing I can relate to her with though. I enjoy making stuff, although it might not turn out very well.
Trixie, or Rainbow Dash. While I deftly try to avoid being arrogant, I'm very competitive and enjoy showing off greatly. These days I'm much more humble, but I've never been able to keep my passionate side in check. Akin to Rainbow Dash (to some degree), I do enjoy a bit of athleticism here and there, and at the same time (like her), being lazy. I also particularly relate to Nightmare Moon's sarcastic disposition.
I'm like Dashie (lazy) and Twilight (kinda smart). At school I'm a bit like Pinkie (random). At home I'm like Spike (no-one likes me).
I'm Fluttershy because I can be very shy and timid and also I have very low self esteem...I'm also like Twilight because I'm very studious and love books.
I've always considered myself sort of a cross between Pinkie Pie and Rainbow Dash, with occasional Fluttershy or Rarity moments.
I'm like Fluttershy in that I enjoy mingling with nature more than I do with others, and I sometimes have a bad temper that seems uncharacteristic for me. At the same time, I'm somewhat like Twilight when it comes to believing in things, because I'm one of those 'see it before you believe it' kind of people. That, and I used to put schoolwork before socializing in a similar fashion to her as well. On the opposite side of the coin, I have nothing in common with Pinkie or Dash, and only minor similarities with Applejack, and Rarity. I like to think I'm honest, and generous for the most part, but that's really it for them.
I'm like Fluttershy, Big Mac, Twilight and Applejack. When I play video games, than I'm like Rainbow Dash and sometimes on meetups I'm little bit like Pinkie.
According to some personality test I took sometime last year, I'm like 50% Fluttershy, 40% Applejack, and 10% Twilight. It seems about right to me. Though it sucks living in a world made for extroverts... I suppose it could be worse.