You are overestimating the value of DPS in WS calculation. DPS is used to improve WS damage so that lower delay/lower damage weapons like Garuda remain competitive against weapons with higher DMG/higher delay, not mop the floor with them. While it's true most MNKs will see 60 WS:40 AA damage in an ordinary fight and 70:30 in an extraordinary fight, this doesn't mean a weapon should be reduced to its DPS stat. There are other ways to increase WS damage--things the community has quantified.
40 INT is enough to send any MNK in AF head to the known INT cap. I understand you don't need INT from your weapon, but this is a transitional weapon until OP obtains INT from other sources.
Which is best for OP right now? That depends on the rest of his gear. If OP were to plop one of the two into his weapon slot as he is geared now, I would say Garuda is better for the sake of ACC. However, for overall damage, he would get the most improvement from sanctified GC hooks and ACC in one of the accessory slots. If Sanction is lost, he can fall back on Garuda or hooks as they are (I suppose it's too bold to claim Ifrit is better than unsanctioned hooks, or vice-versa, in any practical sense; for the sake of inventory space, lose Ifrit once you get hooks.)
