Is there a niche you avoid for religious or moral reasons? Or just doesn't 'sit right' with you?
Is there a niche that bores you to tears?
Personally, although I love animals, I'd never go into the pet niche. I find it all a bit too saccharine sweet for me, and some animal lovers are quite militant and a bit freaky. There are already enough scary cat ladies out there without me encouraging them.
I'd also never do the adult niche. I just don't want that kind of stuff on my computer. What if my kids find it?!!