I've had both cards and settled on the 290 because my monitor wouldn't work with the 780 in 3D.
They are literally the same speed, except when Mantle picks up then 290 will obviously be faster in some games.
The 780 definitely ran cooler, they are about the same level of noise.
It all comes down to what you want.
Nvidia - Shadowplay, Physx, Gsync (Will possibly get Mantle at some point)
AMD - Freesync, TruAudio, Mining, Mantle etc (will get shadowplay equivalent through radeonpro)
Basically just go for whatever suits your fancy in regards to the features they come with.
They are literally the same speed, except when Mantle picks up then 290 will obviously be faster in some games.
The 780 definitely ran cooler, they are about the same level of noise.
It all comes down to what you want.
Nvidia - Shadowplay, Physx, Gsync (Will possibly get Mantle at some point)
AMD - Freesync, TruAudio, Mining, Mantle etc (will get shadowplay equivalent through radeonpro)
Basically just go for whatever suits your fancy in regards to the features they come with.