I'm in jb's boat; waterfall without a filter (and a bog AS my filter) with similar water quality. And I'd do as dp says; I put it where I wanted to best see it. With regard to your leaves, I think you're probably going to invest in a net to keep all the leaves out of your pond anyway, so maybe plan on it now? And put your waterfall where YOU want it???
For my setup, I have the waterfall (upper rt corner) and river (flowing FROM the bog = rt side, lower right) into one end while my submersible pump sits at the other end (left).
and with a waterfall, you can do this!
Michael