I like writing that makes me laugh; that has a bit of a comical or whimsical twist in it somewhere. Writing that is darkly funny is particularly good for me.
The opposite -- maybe I'm a literary prude; but I cannot abide writing with obvious errors...it can be the most wonderful moving piece, but if I come across a typo or a misuse of a word, the moment is gone for me -- coitus interruptus. That doesn't apply to things that are "informal", but if it's supposed to be a polished piece...well, then polish it, dammit!
I like writing that pulls me in, even when I'm uncertain it's where I really want to go, and traps me....holding me prisoner.....forcing my eyes to the next word, the next sentence, the next page....capturing me wholly so that in the end I never want to leave it.....and then when I do, it makes me evaluate, not only the writing itself, but the world in which I live as well.
I like writing that feels like its always been there. Nobody had to think of it, someone just had to write it down.
That also applies to the act of writing, the feeling that the words have always been inside you.