given that most of the exp you gain via FATE grinds is actually from the fate reward and not the killed mobs, on atls FATEs do not fully utilize the +50% bonus exp on kills.

Dungeons and grinding mobs in an area with a lot in a light party or full party (and hitting up select FATEs in the area) can actually yield as good or better exp (need to ensure the hole group is gaining exp chains by mobs being at least lv of highest level in group). Dungeons are fast and near instant queue if you use your friends and FC to fill 3 or 4 of the spots.