Books could literally be written on this and it wouldn’t surprise me if they had been. I ask why choose! Both are wonderful forms. Both have classic examples. Both are entertaining, make you think, invent other worlds and stretch your mind. Both should have memorable characters and incidents.
The big advantage of the novel of course is you can have a lot more of those than you can in a short story. Yet the short story’s big advantage is that having to focus on fewer characters and incidents makes it a more intense tale. It all depends on whether you fancy a long or short literary “drink”!
For short stories, I generally prefer the word count to be under 5,000 (and ideally for me to be between 1000 and 2500, I like my short fiction to be literally short and sharp!). I also like a well crafted piece of flash fiction. I admit though the novel in many ways can be “easier” to do - you have the space in which to expand your ideas and cut backs can always be done later.
How many drafts do you write?
It depends on what I’m writing. For a novel I usually do at least 4 drafts (get the story down, first copy edit as I type it up, then an edit to make sure story makes sense and then a final look over to make sure I haven’t missed anything).
For short stories I tend to write to screen, print out, edit on paper, put in my amendments, print it out and read it through. If it’s good enough I then send, if I find I’ve missed something I do another edit on screen. Scripts I tend to do at least three drafts usually to get it down to the right kind of length for a radio comedy slot.
Do you outline or “wing it”?
I used to wing it even with the novels. Looking back I think I must’ve been nuts. I outline for almost everything now, even flash fiction (though the outline is suitably shorter!). I find for short stories I need to rough out an idea before I can start. With the novels I don’t plot out everything but the main points I need to reach.