I've had a discussion with several people on this situation...
There are several factors and situations where one spec can definitely conquer another. Feral permits for a druid to run at a constant 30% run speed (before debuff) and apply slows while easily getting away and healing back to full. On the other hand.. once debuff hits, the prime reason of being feral becomes obsolete. Resto on the other hand allows a druid to have good constant healing and mana regen at the same time, being capable of popping a clutch heal with Swiftmend. I don't really see the extra stam really as a huge factor when deciding on specs, but I rather focus on survivability.. An FC that's spec'd as resto who also knows his jumps and routes can be very difficult to kill. Resto becomes much more viable in pugs, where it isn't too safe sometimes to rely on a healer sticking on you 24/7, while feral would be optimal in a premade situation where having a mobile healer and a CC helps a lot more.
Basically in conclusion, feral for premading and resto for pugs.