Horizontal continuous view.
Frequently when I'm reading a document in .pdf format it's because it has graphics or illustrations in it, the problem is that online .pdfs are often missing pages, have additional pages, or for format reasons don't line up their double-page spreads properly. Currently Evince supports vertical scrolling, double page vertical scrolling, and single and double static pages. To correct misaligned graphics you can select which side even or odd pages are on.
Because of the inconsistency of online documents I believe continuous horizontal scrolling is an elegant solution to the problem, both on desktop with scrolling rebound to move forwards and backwards in the document instead of vertically but also on mobile/tablet/convertable, where scrolling horizontally with a touchscreen is not unnatural at all. It's a setting I'd most likely leave on, because it would save me a lot of time messing with the view controls.