Fics posted within a few days of a movie releasing always have a lot of kudos, regardless of whether or not they deserve it. It's usually due to people being excited by a new pairing or fandom and rushing to read whatever is posted.

Aside from that, name recognition is a big thing. I know there are some tropes I've scene over and over again, but I'll read them if an author whose work I like in another fandom writes a fic with that trope.

When fandoms become so huge, so quickly, a lot of good fic gets passed over and it takes fandom awhile to find it groove. Across every fandom I've been in, there's always been one or two fandom favorites that I've disliked. I think it comes down to preference and what the majority of fandom is seeking at the moment.