Great poll and question. Agree the 2-4K is the sweet spot. As a writer I typically fall into that range, not by design but probably because I run out of ideas or motivation. As a reader, same sweet spot but if the quality is there the word count is less important. In all the cases I can think of over 4000 words it was a series broken into smaller chunks of 2-4K. Like others above i want to know about the characters, what they are thinking and feeling, who they are. I love browncoffee's work, I loved how she would get inside the heads of her characters. (One example, many great writers here do this.)
Coincidentally, have 32000 words of a new story (non-erotica, may go on sister site) so this is rather timely. There are some good natural breaks that will keep a Chapter to 2-4K but in other spots I'm wondering what edits I might need to either create a break in the right spot or link the end of a chapter to the next chapter. Also toying with the idea that each Chapter would stand on its own as a "read'. (difficult because the story builds on the previous and the reader would miss some of the context.) I'm expecting the story will reach 40,000 words and I'm already editing heavily. Its crossed my mind to only post the ending Chapter because i think its the strongest and I'm pretty sure if I post 8-10 Chapters by Ch 10 all the readers will have dropped off and NOBODY will read the ending.