Of all the assorted protests I saw, I liked what interestingasfuck did the most. Just said "f it, here is what subs will look like with the bare minimum modding" and walked away. Mess up their front page, their advertising, and actually show what an unmodded major reddit sub would look like.
If every sub had done that instead of some milquetoast 48 hour blackout, I think it would have been at least moderately more impactful.