Why not all of them? Do you not play in Union events?
If you can get your ass into one of the top15 or even top30 Unions (that's 450/900 players out of the Nutaku Kamihime ~1000 playerbase), you'll be getting lots of Shards. And if you are interested in the Union grind, then Phantom Elemental Lord Thor is by far the most valuable Hime in the entire game. Hell, if you're willing to manual Thor for 8-16 hours for one day per Union event, you can easily find yourself in any of the top5 Unions I'd imagine (not that we currently have a set top5).
If that's not appealing to you, then either reroll into a 100% Eidolon or Satan.Text is not a good medium for jokes and sarcasm.