These stories are those that I absolutely enjoy the hell out of.  I recommend at least giving them a looksee, if you like them, make sure to let the author know!

Most of 'Art Inspired's work makes it into this list, every time he posts a blog, i get at least 13 notifications.

'Eternal' by 'device heretic  One of the only two very popular fics that made it to this list.  The other is Past Sins.  This story has driven me to tears.  It's so well written, it was the first story that i ever actually keep a copy of saved on my hard drive.

'Sunset' and it's sequel, 'For Want of a Dawn' by 'Ciroton.  It has Twilight find out something about her past that Celestia would rather have not been found.  These two have found their way to my hard drive.

'Not my Destiny' and it's in progress sequel, 'Glim' by 'Smayds'  This is a TwiAlicorn fic, but it goes completely differently than other TwiAlicorn fics.  This one tackles the aspect of immortality, and what that means for a mortal to no longer be as such.  Be warned, these are a pair of sad grim/dark fics.  The original has a place on my hard drive, and it's sequel does as well, when it finishes.

'Yours Truly' by 'Thanqol'  This uniquely portrayed fic shows a romance between Twilight and Applejack, and what happens to them over the years.  The form it's in helps it show how much emotion is packed into those words.  It's a nearly 19k word one-shot fic.  I'm not afraid to admit tears were shed on this one.

'Past Sins' by 'Pen Stroke' This fic is the second of two 'famous' fics that i've read.  If you've not read it, do so.  Now.  It's well worth the effort put into it.  I've actually ordered a hardback copy of it, and that will be why it won't have a place on my hard drive, i'll have a physical copy to hold.

'Mortality Report' by 'Bad Horse' This is a take on what happens between Celstia and Twilight when Twilight's natural time is up.  I'm not going to spoil it, but i'll be damned if i don't say it's not emotional.  That [sad] tag is the only one, for a reason.

'The Light Goes Out' by 'AbsoluteAnonymous' This fic is similar to, yet different enough, from Mortality report that they don't seem repetitive.  Read them both.  Do yourself this favor, please.

'Through the Eyes of Another Pony' by 'CardsLafter'  This story's actually a rewrite of the original, by the same author.  Chapter fifteen is part of the original story and doesn't make any sense as of yet in the rewrite.  This is the only story so far, to have left me in tears from laughter.  And with good reason too.

'Oldnew Luna', and it's sequel, 'Oldnew Luna: After the Dawn' from 'arandompenguin'.  I'm currently helping edit these two stories to improve their quality.

'Equestria from Dust' by 'soundslikeponies'.  The imagery that's created in this story is so vivid, it's hard to describe.  It'd be easier to compare to a photograph translated into words.

'Zer0 H0ur' by 'Vorizmordu' This is a FIM/Borderlands 2 Crossover.  This story's not told in the typical crossover sense, it's actually set more like a HiE fic than a crossover.  Still a great read.

'My Little Borderlands: Friendship is Badass' by 'Bigwig6666' is another FiM/Borderlands 2 crossover.  This one goes the opposite direction of Zer0 H0ur though.  This one is kind of a universe swap from Zer0 H0ur.

'Just over the Horzine' by 'Some Person' is another crossover.  This one's rated 'mature' for a reason.  It's a Killing Floor / FIM crossover.  It's gritty, depressing, and downright morose at times, but it's all because of Killing Floor's atmosphere.  It's not quite 'horror' but definitely fitting of it's 'Dark' tag.  This is the only Killing Floor crossover i've read, to date, and it's still one of the best crossovers i've ever read.

'To Love the Moon' by 'Indigo Eclipse'.  This one is different than the rest, so far.  It's a clopfic.  It's also much more than that too.  The relationships portrayed here, feel so real that some of the time, as the reader, i feel like i'm intruding upon a private moment.  It's not all romance, though.  It should have an 'adventure' tag though.

'Secrets by 'Fiddy' is a little known story.  It stars a semi-Mary Sue (Technically, Gary Stu, as he's male) character, Wildfire.  At this point, it's just getting started, and i can already tell from what i've read so far, that i'll enjoy this story immensely.

'What Happens in Terraria' by 'BioChemicalWolfGear' is a somewhat different crossover.  It started out as a crossover, and has shifted into a true HIE fic.  I'm also currently editing this to improve it's quality.  I only started at chapter 20-ish, so i've not had time to go and touch up earlier chapters.

'Memoirs of a Reality Jumper' by 'Techogre' and it's side story 'Applejack's Diary', A really well written HiE fic.  The side story provides another character's perspective on the events in the main story.

'Ascend' by 'xTSGx' is a unique take on Twilight becoming an Alicorn.  It's got the comedy tag for a reason, and has left me in stitches more than once.

'Five by 'CookieMonstar' is one of the better stories i've had the pleasure to read.  It's currently under revision and thus, all chapters have been pulled down.  When they go back up, i imagine they'll be better than before!

'Rites of Ascension' by 'CvBrony' is one of the better TwiAlicorn fics i've read.  It's a true adventure story as well.  Even if you don't like Twilight as an alicorn, still give this one a shot.  It's probably not what you're expecting.

'The Quiet Place' by 'Aynine' is another TwiAlicorn fic.  Like Rites of Ascension, it's an adventure.  This one's a dark-adventure though, and it shows.  I like this one nearly as much as Rites of Ascension, just because of the two different directions both authors took with their stories.

'Taming the Rage' by 'Fire Soul' is a rather depressing story.  I recommend this story highly, and don't want to spoil it here.  It's tags are [tragedy][sad][dark][Adventure][Slice of Life][Alternate Universe], and the first three tags, plus it's description initially put me off.  I'm glad i didn't skip over it.

'Mane Effect' by 'Quillery' is a FiM/Mass Effect crossover.  This stays true to both sources' material, yet combines them effortlessly together.  An absolute blast to read, if you loved the original Mass Effect.  I imagine at least ME2, and hopefully ME3 as well, will be done as well, but i'm just speculating at this point.

'Four of Two' by 'Ariamaki' is a romance story of technically four pairings, focusing on two.  Those pairings are Twilight/Celestia, Luna/Fluttershy, Rarity/Applejack, and Rainbow/Pinkie.  It is a clopfic, but not in the traditional sense of a one-shot.  As of writing this, there are 45 chapters (counting a few (six) intermissions from pinikie or a flashback), Ariamaki, the author of this story could easily just be an artist and somehow translates his visions into words.  He paints such a vivid image of each scene, each action that i couldn't help but sit back after reading a chapter and let the... movie, for lack of a better term, play in my head of what i just read.  The story, while sweet, isn't sickeningly so, and each character seems more alive than the crap on TV these days, let alone the actors behind them.