Flordiel

For building quick faction with Flordiel you can go to the outpost in Ruin Falls and you will find a crafting area with representatives from the 3 factions, including Flordiel. You can take Work Orders from the Flordiel representative and upon completion you will receive 500 faction per Work Order (and negative faction with the other two). So in order to become non-KOS with Flordiel (which allows you to receive all the armor quests) you only need to do 4 work orders which should take no more than 10-15 minutes. No need to bother with the Atonement quest.