I'm Julie and I mostly read Harry Potter fanfiction, but sometimes get a craving for some Supernatural, Star Trek, Doctor Who, Lexx, Firefly, Lost, Batman, Lost Boys, and Buffy. I haven't posted anything I've written yet, but I'm working on getting up the nerve to do so.
My favorite Harry Potter characters are Severus Snape, Remus Lupin, Neville Longbottom, Hermione Granger, Luna Lovegood, Sirius Black, and Draco Malfoy, pretty much in that order. I'm not rabid about any pairings, so I'm just as happy to read a good Hermione/Ron as a good Hermione/Harry, or a good Harry/Draco as a good Harry/Ginny. I don't see what the big deal is about being so attached to one pairing that you need to bash all others, so people who do that kind of annoy me. As long as it's well written and justified, I don't care what the pairing is. Even canon pairings can be just plain awful if the writer doesn't do squat to make it believable why those two people are together, relying instead on a shrill cry of "But it's canon!!"
There are a couple of fanon clichés that I don't like much, and they include superpower!Harry, weathy/pureblood!Snape (usually with an ancestral castle and inherited rare powers or some such nonsense), ridiculous amounts of wealth for any character, dumb and unnecessary original characters whose role could have easily been filled by a canon character, deadlyabusive!Dursleys, and the kind of benevolent!Dumbledore who forces others into annoying situations "for their own good" and against their will.
On the other hand, there are some clichés that I do like, such as the "mate for life" werewolf one, Slytherin!Harry, Snape as Harry's dad (bio or adoptive), and herbologygenius!Neville.
If I went to Hogwarts, I would be a Ravenclaw, but the Hat keeps trying to stick me in Gryffindor when I take sorting tests. I don't see myself in Gryffindor... I think I'd leave!
That's about it!