In selecting the stories for Science Fiction Trails, where I'm editor, I've found things tend to run in themes. One reading period will be heavy on alternate worlds whilst another might be heavy on professor/inventor type stories. And then sometimes there is no clear pattern, just a little bit of everything. For issue 14 I thought we might be heading into another steampunk issue. Alas, I got a few steampunk stories but I only accepted one of them.
I also got a few little green men stories. And I liked them. I've always been a sucker for stories with little green men in them. They don't literally have to be green, but merely aliens from outer space. I'm not really sure why I like these stories. But I do seem to like tales of flying saucers and space aliens--especially if they're doing something interesting. I'm still haunted by the time I got a ton of aliens in caves and mines for no explicable reason.
What I wish I could get are more stories from the ologies. By that I mean geology, biology, paleontology and so on. Too many submissions fall in a very narrow and often predictable range. I can always hope.