Eorzea Database

While this drops off both lesser and fully-fledged gaganas, I have to recommend going for the latter. As Winter York mentioned, they're all clustered together conveniently, which makes for an overall steady droprate compared to the scattered lesser gaganas. Here's my route:

1. Start just north of Vira Nilya at 27, 18 to find one gagana.
2. Make your way to 29.4, 14.3 by moving alongside the left side of the canyon, killing a group of two gaganas and one lone gagana along the way.
3. Double back and take a fork in the canyon to 30.4, 16.7, pummeling three more gagana.
4. At this point, you'll need to wait for respawn. What I did was move toward Djanan Qhat around 32, 15.7 and beyond for some marid hides. I was leveling my LTW, so I knew I'd need them later for marid leather.
5. After killing the four marids within easy reach, I doubled back to Vira Nilya to start the loop. Usually, I'd make it back just as the first gagana respawned.

Happy hunting and good luck with LTW!

The Lesser Gagana seems to have a much higher drop rate, in my own experience.

Go for the fully-fledged Gaganas. Not only are they in a convenient canyon for farming, but their drop rate is *much* better than the lesser.