There was the nightmare and its realm and the envy's dream world both of which were far more disturbing than anything that was in the previous games, there is that manor in the Emerald Graves with its undead and dark backstory, that mining town region with the red lyrium growing everywhere with the towns people being used as slaves to mine and grow Red Lyrium by the red Templars.
I personally didn't Nightmare that frightening - its design was horrific and well done, but to me it was more of an interesting concept than something disturbing: its realm looked much like any other part of the fade, albeit with some horror creatures running around (manifested as spiders) on top of the usual demons. Envy's projection was interesting too, but as it was completely conjectural, I didn't feel that it carried anything near the same weight as the alternative future seen in the mage quest. The other examples that you gave are in my view too peripheral to the narrative, and though disturbing are only very minor aspects of the game and not experienced very personally.
In DA:O meanwhile, almost every Origin story ended in some horrific manner and we as players experienced every part of that. The human noble's family, house and allies wiped out, the dwarf noble betrayed and then ostracised by his/her society, the dalish elf losing his/her best friend then later seeing him as a grotesque, twisted creature, the city elf's experience of the rape and murder of family and friends by a noble etc. But worst of all for me was the broodmother reveal (in regard to how the darkspawn reproduce) which in my view is the most disturbing thing ever written in any Dragon Age game or literature. Other dark aspects of the main narrative would be the entire Redcliffe arc and the mage tower quest.
Ultimately, what we decide is disturbing is going to be very subjective, but I do feel that DA:O had a lot more dark fantasy aspects at its core and furthermore did overall feel more realistic than the more flamboyant Inquisition (in its culture, architecture and depiction of society and class: as this thread demonstrates). The styles of the two games are markedly different, and I see Inquisition's style as much closer to high fantasy than to dark fantasy (in relation to Origins).