There is a guide in OP for which stage yields best number of FW accordingly to your stamina.
If any advise, do phase 2. They have more FW than phase 1. Since you are at level 50+, you can do E-6 or E-7. You can try E-8 if you have enough girls(at least low level evolved or equip with ring) along with strong helper. Be sure to do phase 2 Secret Garden as it has FW only as rewards.
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