This is a question I struggle with from time to time. It seems the most natural lengths that come out of my pen are 70k words and 150k words. Grr.
I made this table based on Ralan’s compilation of the major players in publishing these genres. I point out that these are preferred lengths and not strict limits. A friend of mine published his first novel with Baen and it was 150k words.
All things being equal, however, it makes sense to target the lengths that your publisher wants. It turns out that books in about 100k in length will work for any of them, and so that’s probably the length you want to write.
|Publisher||Min Length||Max Length|