I probably should have saved a version of what I put in my form. I don't remember much of what I said I disliked, so take that for what you will. If it didn't bother me enough for me to remember it, you're probably okay to write about it. (There are two things I don't really read).
I have a very special place in my heart for Kevin Tran, so if you include him in some way, I'll probably melt into a happy puddle of joy. Most of what I write and read is Hurt/Comfort, but I occasionally go beyond that and read case fic, fluff, some dark fic once and awhile. I like happy endings, or at least endings that provide some closure.
Two Things I don't really read:
1) Character death makes me sad and I generally avoid it, unless it's canon. Bela Talbot, Bobby, Kevin, all of the Winchesters yeah, I can deal with it if it's in a canon sense.
2) End!verse and fics where the brothers retire/stop hunting/one of them dies for good this time. I have read some pieces like this that I loved, but it's not my usual cup of tea.
I hope this helped you a little :) Happy writing!