At the end of the Day there is no true answer ....

I use Eos because I'm in cleric like 85% of the time now in FcOB ...so I figure the plus 20% heals to the WHM on top of a 500 tick whispering dawn every minute help the WHM Heal a lot easier while I focus more of the DPS aspect of our job. Selene is very useful and if healing is a non issue I would suggest using her unless you plan on dpsing ...her heal out put is viable but you lose 20% raw healing ability on top of AOE HoT heals with Selene in the picture....Fey Illumination x Whispering Dawn + Rouse has saved a wipe from missed towers on a many occasion as the tick is on par with the bleeding on top of a WHM Illumination + Medica II so Eos is very viable option even while farming.