Young Love by Ekusukallybaa, because wao is that seriously amazing. Synopsis: Sasuke has a very good reason for avoiding Konoha. Her name is Naruko. Includes yanderes, bad ass Sakura, and Sasuke praying to the shrine of his 'comrades' for their sacrifices (in avoiding the yandere). Beautiful. *winks back a tear*
So Not My Problem by Sarah1281. Because she is a writer who is unparralled at writing dialogue that is 1) true to nature and 2) seriously witty. I love the back and forwards her characters hold, just, gah. No words. Though this one story of hers in particular can be said to be my favourite because it was the first story I read of hers, and it has an emotionally stable main character, which is difficult to find in fanfic nowadays. Though I guess 'smart, witty and uncaring' doesn't necessarily mean emotionally stable to most people, it does to me.
Fire Demon by Minnionette. Or any other of her stories. Because she is by far the greatest writer I have read on this site. By far. Why? Because she can actually come up with her own plots, that's why! A genius at making up her own settings and have them make sense and be completely self contained. Masterful at writing both the comedy and horror and everything in between. The only downside is that this story of hers in particular she hasn't actually completed (it's been 2008 since her last update). And...I am going through so much withdrawal because of it, it is legit terrible. *sad face*
Chimera by Kiana Caelum. Set in the Night World series, this story has it's own setting and characters and feels very much like it's own self contained story rather than fanfiction. Synopsis: Chatoya Irkil is a witch and thus able to use powers to that end, and unfortunately for her she is going to have to, because her soulmate Blue (who she met when he was trying to kill her friends and wants to kill her) is up to something. Is a suspenseful thriller with lots of cool action rather than a romance, thank god. *grumbles*...but I guess there is some romance too for those who like it. ...If you can call this romance.
Embers by Vathara. Again, masterful world building which borders on original fiction, but containing the characters everyone knows and loves. Main character is Zuko. Does contain slight ooc'ness in some characters like Katana, but the quality of the writing by far makes up for it, and besides, the world building justifies it.
And for other author recommendations... EarthScorpion's and AzureShadowMoon. The first for writing good, complex characters and nice worldbuilding. The second for being a wordsmith, I swear to god, who is good at humour, tragedy...just about anything. Her character interactions are pure gold.
Oh, and BFTLandMWandSEK writes nice believable characters too, with inventive and original plothooks. Lomonaaeren too--she's really good at charaterization, to the point that all of her characters feel like they could stand alone on their own merits in any book.
DeGlace has also joined the list! She may write rare pair hell, but she's really good at coming up with amazing plots. Also, her romance ignores every cliche! It's shameless and also somehow hypnotic. Cannot tear my eyes away. Every word counts.
Meanwhile, firefly writes absolutely splendid one-shots of amazing characterization and language skills. Just, ooff! And Luki Dimension's bleach one shots--especially her Ikkaku and Yumichika ones, are just so outstanding! Give them a try.
Esama is also good at crafting original one-shots. I especially like her Final Fantasy 7 fics.
Killaurey's Naruto one-shots are great if you're looking for complexity and female characters. Very nice.
Lastly, Starlineshine writes good emotive stories you can get lost in.
...And asserted other reccomendations when I bother to put up more.