Jfmam here. I'm just writing a couple of things here on the off-chance anyone finds my profile.
Firstly, last time I checked, I can't write fiction. I can't rule out making an attempt in the future, but that won't happen until I work on my story writing skills.
For the time being, I'm here to read fanfiction. Starting out, I was just reading DB/DBZ stuff, but I'm finding myself branching out a bit now.
Though currently I can't write fiction to save myself, as a reader, there are a few things I look out for.
I tend to prefer stories that stick to canon, and particularly those that retain the original tone/feeling of the work. AU stories can be fun though, it all really depends on the plot and writing. Generally, I feel that keeping characters in character is important. For all the weirdness and fantasy a story can have, if you can't hear the original character's voice in the story, it can pretty quickly pull you out of the experience. Obviously, things will be a bit different in AU stories, though I believe that even then, a good story will latch on to a fundamental aspect of a character, justifying their use.
Of course, like everyone else (who isn't a writer), I'm here to read enjoyable stories, regardless of if they keep to these 'rules' or not. I guess if I ever write myself though, I'd try to keep these ideas in mind.
If I start writing or anything like that, I'll announce that here.