Oh gosh, this is going to take a little bit, lol. I’ve read so many it’s hard to remember them all or pick from them. Uh, let’s see…
For favorites, in no particular order, both popular and unpopular (not really sure what most the most accepted classification of “popular” and “unpopular” is, but generally I consider it to be unpopular if I rarely or never see people talking about it/rec-ing it in comparison to other fics, and I consider it popular if almost everybody has read it or at least heard of it):
And I know I’m forgetting a lot, because this was just kind of randomly done off the top of my head (even though I have a list 127 pages long of Destiel fic), and I have a really crappy memory. And I could spend hours thinking about this, which I figured I probably shouldn’t do. I’ll probably remember more later and be like “shit, how could I forget that one???” Also I only named longer stories, there are a lot of shorter ones and one-shot’s I’ve liked too.
Lol, I think I’ll take you up on not having to answer the second part, because I don’t want to offend anyone. (Also I try to put bad ones out of my mind so it’s harder to remember them on the spot.) But I will say that other than obvious things that make a fanfic bad (like bad grammar and being poorly written/thought out), I don’t like when put in permanent major character death without tagging, or have the characters do something really shitty/ooc without tagging, or when Destiel turns out to not be the endgame pairing (I can usually grudgingly tolerate most Cas/other and Dean/other as long as it’s not significant/ends quickly).