For WS's you'll want to look at the base damage above all else.
DPS is only counting the base dmg and the delay on the weapons. It doesn't factor in the additional crit+/atk+ etc that most weapons feature - so keep that in mind.
Think of DPS as damage over time. A higher DPS weapon will yield more damage over a long battle while a lower DPS weapon that has a higher DMG will yield higher results in a short battle.
Get both, use one for running through mobs on the way to a boss and the other on the boss itself.
EDIT:
You can also base the weapon on your playstyle/gear-set. If you have a heavy crit-based gear-set/playstyle go for Garuda's. If you're going just for raw attack power in your gear/style then Serpent Lieutenant's Claws will yield more of a return and higher weapon skill damage.
On the whole I'd go for the Serpent Lieutenant's Claws. They have a lower DPS just because they hit a little slower but if you have 2 BRD's and that LNC ability I can't think the name of that gives TP then you'll get a much higher return by being able to WS more often for larger numbers.
If you factor in the Sanction buff of attack power+25, the DPS will be higher than Garuda's Talons in a long fight. Just remember it only lasts for 2(?) hours and will wear off if you die.