I'm glad this thread was made to hopefully finally clear up this misconception.
Titan- solo (obviously)
Garuda- aoe/ slight mp management
Ifrit- single target dps

Raging strikes cooldown is just too long to make garuda a better choice. She is by far the better aoe pet. Bane/contagion combo plus her higher damage from magical attacks is far superior to ifrits physical damage plus an Autoattack on 1 enemy