First, yes, you are thinking about this way too much. Write for yourself first, that way you'll put more heart and soul into what you come up with. Making your story accessible to others is a second-draft thing, not a first-draft thing. However, given the length of this response, I'm also obviously thinking about this way too much, so here's my longer and less helpful answer:
I'm more inclined to read works that pull you in quickly. I force myself to completely play and write a looong review for each game I read, so I tend to avoid committing myself to games that don't seem like they'd be worth the effort.
For literary games, I like pretty much the same things in storygames that I like in traditional fiction, such as engaging characters and well-developed settings. There are a few themes that I personally like, such as stories about developing competence, and stories with a lot of humor, but my personal preferences probably aren't very helpful to you.
If you're specifically looking to attract readers, I recommend choosing a target audience and sticking to it. Then, you ignore the complaints of anyone who doesn't fit the description, and pay close attention to the complaints of those you do. As a writer of storygames, your choice of a target audience is already very limited.
Any genre or style of story can work with the choose-your-own format, but I think the format lends itself well to puzzle games, combat or challenge based literary games (such as a quest or spy mission), stories where the protagonist's choices will have far-reaching effects on the setting (so you can see those changes play out in different branches), and large-scope stories that allow the protagonist and setting to change greatly over time in a variety of ways. I like to see stories that really take advantage of the interactivity this format provides, and do more than just show the player a series of related stories.
As for what's popular/preferred on this site's target audience specifically, here's my general impression of what people like:
-The setting is richly detailed and complex. It will often be fantasy or sci-fi, but a real world story can also have significant lore.
-The protagonist can make morally gray (or black) choices that don't lead to immediate death or endgame links.
-The plot and events are large-scope and consequential, and the protagonist has the power to majorly affect them.
-Puzzles are not as popular as other games, and should not be too difficult.
-There's a surprisingly large number of popular stories about the protagonist practicing necromancy, demonology, or some other form of dark magic.
-Games that poke fun at or play into traditional fantasy cliches and plots.
-Games that have a protagonist with a strong and distinctive personality, sometimes an abrasive or antisocial one.
-Games that have easily accessible endgame links.
Am I missing or incorrect about any popular CYS trends?