Original thread (which I found extremely useful) on the EU forums by Invino.
Not all quests are added since faction revamp, tho this still helps
Won't bother with N.Grasslands and Chosain so just Kara Korum and Paikang ones.
Posting just names and locations of Repeatable Factions quests. There are once-only aplenty around.
Tip: Check Ghost Hill in KK area as you hit ranks as there are scrolls, bodies and pages on the ground that give some quests and/or start chains.
Tip: For Last Legion fans: Both BB and SoJ have quests in SC palace (KK- PraEun), but here is a shortcut; No need to kill all to get in, from the entrance run all way to the ladder leading down to the prison - kill 2 guards is better than 15 SC. Just climb ladder and go up - kill as needed. ** to avoid main room, go to the end of the basement and climb the other ladder **
Tip: Jiang Shi faction is a must for all really, especially Brittle Blades due to overlapping quests and nice MoA gain.
Tip: If you got enough MoA to burn: buy 20 MoA AA vases from Mystic Supplies merchants. Best used when AA pot running.
Rank 1 = 50k faction, Rank 2 = 200k and Rank 3 = 450k