I stopped having issues with Riven...
...after I created a special rune page with only armor runes: Armor quintessences, armor marks, armor seals, and armor glyphs.
That and starting with Cloth + 5 pots make me have a total of about 85 armor at level 1. That value depends from the champion that I am using; I tested that with Zac, using 9/21/0 masteries.
It seems like that is the only way I can beat Riven, as then she does NO damage during the early game and I beat her in her game.
Speaking of which, why people stopped complaining about Riven? Is that because of the Juggernauts countering her?