They say to write the book you want to read but can't find.
Here's the danger:
If you can't find it, there's a 99% chance agents, publishers, and reviewers don't like it or want it.
I'm not saying you shouldn't go for it. Whatever *it* is you're looking for, someone else out there has felt the same.
Write for them (and for yourself).
But recognize that finding your fellow rebels can be a seriously uphill battle, and brace yourself for pushback.
The very thing you most crave might be the very thing the established book market is quickest to reject.