Hey everyone, I figured I would share some of my insights regarding XP farming since much of the data I sought after was not available and I had to calculate it myself. This isn't some end all be all guide for XP farming, but instead to be a useful reference for how you choose to farm out your xp.
Master Writs: Roughly 18k xp per master writ. Can complete up to 7 simultaneously with access to complete guild crafting hall. With crafting addons, it takes 5 minutes to complete a set of 7, resulting in 126,000 xp.
Daily Dungeon bonus is worth 101k, with an average of 30k xp accumulated by progressing through the dungeon. Average time for a low tier dungeon is 7 minutes, a mid tier dungeon is 10 minutes, and a dlc dungeon is 20+ minutes. I advise vote-kick resetting a group whenever you get a dlc dungeon for the random normal unless you specifically need gear from there.
Skyreach nets 60k xp per run, taking just shy of 4 minutes to complete. This method is on par time wise with doing the daily dungeon so long as you do not do the dlc dungeons, however it does not gain you anything useful like doing a daily dungeon will (transmutes, skill points, gear).
Note that Aetherial ambrosias are actually only about 25k at the time of this post, and using the Connoisseur passive from provisioning on top of the Rationer CP makes the otherwise 30 minute xp buff instead last 100 minutes, 3 times as long.
I do writs on many of my toons, but they are all "fake tank dps" ready. I have all their passives/CP allocated to maximize the use of the Aetherial Ambrosias and do my writs, then immediately queue for a random dungeon. A single AA is worth about 8 daily dungeons, with the rest of the time doing the daily writs. With 10 characters using this method, it will take 161 days to go from 810 CP to 1800 CP, while generating 16,100 transmute stones for gearing out characters.
I will update this post with information as people provide it.