I have to make a confession right off the bat. When I am surfing Amazon for a book to read, I steer clear of books of more than 100000 words. In the past, I've generally found they have so much padding, they don't keep my interest.
The first romance I wrote was over 200000 words!! I quickly realized I had too many heroes and heroines, too many lovers hopping into bed with each other, and too many plot twists.
So, I split the manuscript into four separate stories and, voilà, my writing career took off!
In subsequent years, I have tended to aim for 60000- 70000 words. I feel I can tell a good story of that length.
Some readers enjoy novellas and they are fun to write, although it often isn't easy to keep a story short. Speaking of which, short stories are popular, but I can't write them!
A MidWinter Night's Dream is probably the shortest story I've ever written and it was originally created for an anthology.
I prefer longer books. I won't read a Novella as it's just too short. I read the Count of Monte Cristo by Alexander Dumas when I was in the 5th grade. Thoroughly enjoyed it. Started my love with full length novels with no extended episodes.