Well there's these opinions here that might be worth a look I'm not technical at all so it might make more sense to you the numbers side of thing.http://gpuboss.com/gpus/Radeon-R9-380-v ... ce-GTX-780
There's not much on net with direct comparison but all I know is that the 780gtx I have plays everything I have in my library that's current on at least high detail. For instance with Fallout 4 it plays on ultra. On witcher 3 it plays most of the list on ultra aside from a few things that are generally graphics heavy.
The only reason I'm upgrading now is that I have the money and I haven't upgraded in a while and I want a card that will handle VR in the new year potentially.