Well, lets see now, Of the Fanfic I read, I'm quiet fond of a lot of stories though I usually follow a few good writers regularly.
I'll Recommend pretty much everything by
Tim Joy / Jeconais. While He's not posting much new stuff right now, he has promised to finish most of his outstanding stories and is on his way to do so. His Completed stories like "
This Means War", "
White Knight, Grey Queen", "
Hope", etc are some of the best and longest I've read. The best part is that He's recently Added downloadable ebook versions of all his stories in all the major formats so its very easy to download and transfer to the reader of your choice.
Heck I'll recommend trying most if not all the authors he's hosted on his site
FanFicAuthors.net. He's got some of the Best, most consistent writers hosted there including Bobmin, Crys, Tenhawk, Istar, Draco664, Ruskybyte and a few more.
Others whose works I enjoy include
Disobedience Writer, whose stories like "The Horror, The Horror" I find hilarious and other stories worth thinking about.
I'll Definitely suggest checking out
Calum Wallance / DogheadThorteen / Wolfman's works, though I'll warn you while he often throws canon out of the window, all his work is a great read and very entertaining. Check out his Ongoing Harry Johnson Saga as well as The book of Dobby. The universe he's built for the stories is so big and has so many crossovers and influences its hell of a ride. Each of his stories tend to be quiet meaty so is always worth the wait though he is pretty regular about posting updates.
Speaking of regular Writing Machines,
Rorschach's Blot is one of the best and regular writers around with works like Make a Wish, Larceny, Lechery, and Luna Lovegood, Old Soldiers Never Die and Lord of Caer Azkaban to his credit. All these and more are great stories and well forth a read. He also has a very active Yahoo group where a lot of authors publish works in progress to get feedback before posting to FF.net.
Others in the HP fandom I'll suggests having a look at include
The-Cattiff,
Perfect Lionheart,
Nonjon,
CrazyDan,
Clell65619,
Chris Hill,
The-Dreamer4,
Enterprise1701-d &
Daily Prophet Reporting
Of Non HP fandom, I'll heartily suggest Checking out
Chris Dee's Cat Tales. Its a wonderful look at a DC alternative universe, especially if you don't enjoy the modern gritter universe. Even if your not a long time DC fan and just have basic knowledge of the verse (as I did when I Started it) its a very worthwhile read and is currently on its fifth book so there is a lot to read.
Other then that I mainly Follow BtVS, Ranma and a few other fandoms, so if interested I can post a suggestions for there.