I would really love an easy spoiler tag that did the right thing for screenreaders/mobile/everybody. Failing that, I'd like something that did the right thing for as many groups as possible, because the status quo is more bunk than pretty much any of the alternatives.

(I found something tonight that works great on mobile and desktop without needing Javascript, but readers won't get the benefit unless they view the entry in my style, and I won't get the benefit unless the folk I read write their spoiler tags so they'll work with my reading page. That's kind of frustrating.)